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KC-10 Aircrew Training System 

Low Visibility Approach and Landing

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LIST OF EFFECTIVE PAGES
KC-10 Aircrew Training System 

Low Visibility Approach and Landing 

Original 

W845-TOC i 01 JAN 06

TABLE OF CONTENTS 

1.0 INTRODUCTION ............................................................................................... 1-1 

2.0 OBJECTIVES .................................................................................................... 2-1 

3.0 VISUAL GUIDANCE SYSTEMS AND DEFINITIONS ........................................ 3-1 

4.0 KC-10 COCKPIT PERSPECTIVES ................................................................... 4-1 

5.0 LANDING ILLUSIONS ....................................................................................... 5-1 

6.0 TRANSITION TO VISUAL ................................................................................. 6-1 

7.0 LANDING FROM PRECISION APPROACHES ................................................. 7.1 

8.0 LANDING FROM NON-PRECISION APPROACHES ....................................... 8-1 

9.0 AFTER TOUCHDOWN CONSIDERATION ....................................................... 9.1 

10.0 SUMMARY ...................................................................................................... 10-1 
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1.0 INTRODUCTION 

A maneuver common to all pilots, and one of the most challenging any pilot may 

face, is a high-pressure, must-do, low-visibility landing. No matter what the 

source of the pressure, whether from high-priority missions, low-fuel situations, or 

rapidly deteriorating weather, pilots will encounter the need to land successfully 

in trying visual conditions. The key to success when facing this situation for the 

first time is being prepared. 

To be prepared for the low visibility landing you must understand the limitations 

inherent in both yourself and your aircraft. You must anticipate those limitations 

and learn to compensate using all resources available, applying the sound 

principles of Crew Resource Management (CRM) where possible. You must 

experiment with a variety of techniques to determine which will be effective for 

you and your aircraft. You must practice effective aircrew briefings, defining 

clear crew responsibilities and standardized terminology. 

Equally important is to fly a precise approach. The aircraft will be stabilized on 

approach from 500 feet AGL to the runway, (as described in AFI 11-2KC-10V3). 

If parameters for stabilized approach are exceeded the Pilot Flying (PF) will 

execute a go-around/missed approach! 

1.1 References

The information and procedures contained in this workbook have been 

extracted from the following publications: 

1. T.O. 1C-10(K)A-1 

2. AFI 11-202, Volume 3 

3. AFM 11-217, Volume I and Volume II 

4. DoD Flight Information Publication (Enroute) 

5. DoD Flight Information Publication (Terminal) 

6. Airman's Information Manual 

7. KC-10A Flight Instructor Course 

8. Federal Aviation Regulations (FARs) 

9. AFI 11-2KC-10, Volume 3 

10. AFTTP 3-3.KC-10
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2.0 OBJECTIVES

1. After a brief review of an approach plate and the Flight Information 

Handbook, use standardized terminology to describe the anticipated view 

from the cockpit of the runway environment and Approach Lighting 

System at various points on the approach flown. 

2. State the limitations to visibility inherent with the KC-10 and the 

importance of proper seat position. 

3. State the anticipated visual illusions associated with low visibility landings. 

4. Describe different techniques available to the crew to accomplish low 

visibility landings. 

5. Deliver a crew briefing that enables your crew to support you while 

performing a low visibility landing. 
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3.0 VISUAL GUIDANCE SYSTEMS AND DEFINITIONS

Upon arrival at a 200-foot decision height the aircraft may be over 5,000 feet 

from the runway intercept point. This equates to about 20 seconds, sufficient time 

for the crew to exchange opinions on what they are seeing. Some low visibility 

landing techniques require the Pilot performing the landing to divide his time 

between instrument cross check and the outside visual cues. In this situation he 

will be depending on other crewmembers to quickly and correctly define what 

they are seeing. Effective communication at this time is critical. It is imperative 

that a thorough crew briefing, which defines specific crew actions and 

standardized terminology, be conducted. The crew callouts need to be precise 

and accurate. Standardized terminology is the key. 

The challenge for the aircraft commander is to be able to review a diagram of any 

number of visual guidance systems and then be able to clearly define the plan 

and desired callouts by the crew. For example, the Boom Operator may be used 

to call out visual cues either in front of the aircraft or possibly contact with the 

ground to the side of the aircraft. 

Visual guidance systems include the approach and runway lighting, vasis or 

papis, and the runway markings. These systems provide the basic visual 

guidance to transition from instrument flight, using electronic approach aids, to 

visual flight. The approach and runway lights can provide continuous visual 

guidance from just short of the MM through the approach, flare, landing and 

rollout. 

The Pilot can control the lighting systems either directly or indirectly. If Pilot 

Controlled Lighting (PCL) is indicated, the first page in the approach book 

outlines the procedures available to the Pilot to control the airfield lighting 

intensity from the cockpit. If PCL lighting is not available, the Pilot can request 

the Tower to change the light intensities. Lights are normally controlled from 

level 1 to level 5 with level 1 being the lowest intensity and level 5 being the 

brightest. Normally, in day IFR you can expect level 5 and in night IFR 

conditions you can expect level 3. In partial obscurity at night, you may want to 

consider requesting a brighter light setting. However, be prepared for extremely 

bright lights if the obscurity is not present. If High Intensity Runway Lights (HIRL) 

are installed and the obscurity is not present, the lighting can be almost blinding 

and bright enough to destroy your night vision. 

In fog, the Pilot may find that the aircraft landing lights are causing a distraction 

and impairing his view of the runway lighting systems. The dash one suggests 

that in this situation the Pilot consider turning off the landing lights. If you find the 

lights distracting, have the PNF or Flight Engineer turn them off. Many landings 

have been made with the landing lights inadvertently turned off with no 

noticeable effects on the landing. In most cases the runway lighting system 

provides adequate cues for the landing. 
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Approach lighting systems vary widely. A review of Section B of the Flight 

Information Handbook (FIH) depicts over 30 different systems, each of which 

could be modified in many different ways. There is one system of approach 

lighting that is predictable. Any runway that has been designated a CATEGORY 

II Runway also has very restrictive lighting requirements. These runways provide 

the best visual cues available. A careful analysis of these various lighting 

systems should provide the Pilot with all the necessary tools and terminology to 

analyze most worldwide runway and approach lighting systems. Reference 

Figure 3.1, 3.2, and 3.3. 

As you might imagine, accidents have been attributed to Pilots not understanding 

the approach light system. A contributing cause of one short landing has been 

attributed to the Pilot not realizing that the Sequenced Flashing Lights (SFL) 

terminate 1,000 feet short of the runway rather than at the end of the runway. 

Understanding approach light systems helps the Pilot determine his position 

relative to the runway. Also, some systems can mislead the Pilot as to his 

position with respect to the runway. Proper mission planning will inform the crew 

as to the type of runway and lighting system to expect at the destination. A 

thorough analysis of ALSF 1 lighting system, for example, would help the Pilot 

avoid confusion as to whether he is breaking out short of the 1,000 foot roll bar or 

after it. 

The FAA authorizes two basic Approach Light Systems (ALS) for use with less 

than CAT I visibility requirements. These two airfield lighting systems are 

authorized for use with CAT II and CAT III operations: High Intensity ALS 

Category I configuration with sequenced flashers (ALSF 1) and High Intensity 

ALS Category II configuration with sequenced flashers (ALSF 2). When 

operating in areas not governed by FAA rules, a CAT II runway may have the 

CALVERT (British High) ALS. These systems consist of a configuration of signal 

lights starting at the landing threshold and extending into the approach area a 

distance of 2400 to 3000 feet for precision instrument runways. The signal lights 

normally form a single horizontal approach light plane at the elevation of the 

runway end centerline. This light plane may be raised or lowered due to terrain 

features or solid objects within its area. If an object protrudes above the 

approach light plane, the decision height is moved upwards the same height that 

the object protrudes. The RVR value is then also adjusted upward. Airfield and 

approach lighting can be found in the airport sketch data on approach plates. 

Approach and Runway Lighting systems information may also be found in the 

IFR Supplement and Flight Information Handbook. The Airman Information 

Manual also contains a good discussion of Approach Lighting and Runway and 

Airfield markings. 
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Figure 3-1. Approach Lighting Systems.
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Figure 3-2. Precision Runway Markings.
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Figure 3-3. Touchdown Zone and Centerline Lighting. 
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ALSF 1. All lights on the ALSF1 system are white until 200 feet in advance of the 

threshold. Then the red termination light, red wing bar lights, and green threshold lights 

appear. Sequenced flashers start at 2400/3000 feet out and end 1000 feet from the 

threshold in both systems (Figure 3-1). 

ALSF 2. Notice that the last 1000 feet of the ALSF2 is different that the ALSF1 (Figure 

3-1). The red terminating bar and the two pre-threshold red wing bars are removed. 

Two white approach bars are added on either side of the 500-foot centerline bar, 

forming a roll bar 500 feet out. One row of nine red bars is added on each side of the 

centerline, at 100-foot intervals, between the 1000-foot roll bar and the threshold. The 

colored lights are brighter. 

CALVERT I & II (BRITISH). A series of steady burning white lights that form an arrow, 

which ends at the green threshold lights (Calvert I). The white roll bars are spaced at 

500-foot intervals and the system may have sequenced flasher lights. 

SEQUENCED FLASHING LIGHTS (SFL). Sequenced flashing light are a series of 

brilliant blue-white bursts of light flashing in sequence along the approach lights, giving 

the effect of a ball of light traveling toward the runway. These lights are located in the 

outer 2000 feet of both the ALSF 1 and ALSF 2 systems (Figure 3-1). They operate on 

all intensity steps along with the approach lighting system steady burning lights. 

THOUSAND FOOT ROLL BAR LIGHTS. A 100-foot wide row of white lights one 

thousand feet short of the runway. Sequenced flashing lights generally terminate at this 

thousand-foot bar. On an ALSF 2 Approach Light System, Red Side Row Lights begin 

after the thousand-foot roll bar. 

RED TERMINATION LIGHTS. On an ALSF 1 Approach Light System these lights 

appear two hundred feet prior to the green threshold lights and either side of the 

centerline approach lights. 

RED WING BAR LIGHTS. On an ALSF 1 Approach Light System these lights appear 

one hundred feet prior to the green threshold lights. They are 13 feet wide and are 

either just outboard of runway edge lighting or 75 feet from the runway centerline. 

RED SIDE ROW LIGHTS. On an ALSF 2 Approach Light System these lights begin 

after the Thousand Foot Roll bar lights and terminate nine bars later 100 feet prior to the 

runway. 

CENTER LEAD-IN APPROACH LIGHT BARS. On an ALSF 1 or ALSF 2 these lights 

begin as much as 3,000 feet from the runway and terminate 300 feet short of the 

pavement. They are typically a 13-foot wide, 5-light bar that can be varied in intensity. 

RUNWAY CENTERLINE LIGHT SYSTEM (CL). The runway centerline lighting 

consists of a single line of white lights installed along the runway centerline. The first 

light is installed 75 feet from the threshold and continues down the runway, at 50 feet 
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intervals, to within 75 feet of the rollout end. The lights are alternately red and white 

from the last 3000 feet to the last 1000 feet of runway. The last 1000 feet of lights are 

red (Figure 3-3). 

RUNWAY LIGHTING. (Figure 3-3) The runway lighting available on a particular runway 

can be found in the airport sketch of an approach chart and in the IFR supplement. 

Jeppesen Airport diagrams have excellent descriptions of approach and runway lighting 

systems. See the attached example of Travis AFB airport diagram. (Figure 3-4). In the 

Additional Runway Information block note that Runway 21L has High Intensity Runway 

Lights, Centerline Lighting, ALSF-II Approach Lights, Touchdown Zone Lighting, and 

PAPI’s. This particular plate may be out of date but it points out where the information 

may be found. When you compare it to a FLIP Approach Plate for Travis AFB (Figure 

3-5) you see that it's easier to decipher the lighting on a Jeppesen Plate. 

HIGH INTENSITY RUNWAY LIGHTING (HIRL). The high intensity runway edge 

lighting system is the basic type of installation used by the USAF. It defines the lateral 

and longitudinal limits of the runway. The edge lights are white except for the last 2000 

feet, which may be yellow and mark the landing rollout caution zone. The lights marking 

the longitudinal limits of the runway emit red light toward the runway to indicate the end 

of the takeoff runway and emit green outward from the runway end to indicate the 

runway threshold to landing aircraft. 

TOUCHDOWN ZONE LIGHTING (TDZL). The touchdown zone lighting system 

consists of two rows of high intensity light bars on each side of the runway centerline 

and extend from the threshold down the runway toward the rollout end for 3000 feet 

(Figure 3-3). 

RUNWAY MARKINGS. Precision runway markings are shown in figure 3-2. These 

markings are designed to make the landing area more conspicuous and aid the Pilot in 

aligning the airplane and determining if a safe landing is possible. A precision runway 

contains all of the marking elements: Threshold, Touchdown Zone, Aim Point, 

Centerline, and Runway Edge. 

In addition, Pilots should review the following. 

- FLIP General Planning, Chapter 2, Airport lighting 

- FLIP Flight Information Handbook, Section B, Lighting Systems Legend 

- FLIP Terminal Approach Publication, General Information 
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Figure 3-4. Airport Diagram – Travis AFB. 
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Figure 3-5. FLIP Approach Plate – Travis AFB.
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4.0 KC-10 COCKPIT PERSPECTIVES

Every aircraft has a unique geometry that defines the Pilot’s view. 

Understanding the restrictions this imposes is important for every Pilot to land 

successfully in low visibility conditions. Different seat positions, aircraft 

configuration, glide slope angle, glide slope transmitter location, CG, flap and slat 

setting, crosswind, crab angles, gross weight, approach speeds and nonprecision approach course alignment affect the Pilot perspective of the landing 

environment. The Pilot should consider the effect of all these parameters as they 

affect his aircraft. 

4.1 Seat Position

One of the keys to landing successfully in low visibility conditions is seat position. 

Cockpit cutoff or downward vision angles vary with changing seat position and 

thus the visual cues a Pilot will see would change. If the seat height is properly 

adjusted in the KC-10, the Pilot will have a downward vision angle of 20 degrees. 

If the seat is set one inch too low, this angle is cut to 16.5 degrees. If the seat is 

three inches too low, the downward vision angle is cut to only 9 degrees (Figure 

4-1). It can be seen that a Pilot seat set lower than the recommended height 

could prevent the Pilot from acquiring the visual references necessary to 

complete the approach and landing. 

At 200 ft radio altimeter, on a 3 degree glide slope, with flaps 35 degrees and a 

deck angle of 5.2 degrees, the main gear will be 200 ft above ground level and 

the glide slope antenna will be about 224 ft. (The glide slope antenna is located 

in the nose below the Pilots while the radio altimeter measures the height of the 

main gear above the ground). At this altitude the aircraft should be between 

3400 and 3600 feet off the approach end of the runway, depending on the 

location of the glide slope transmitter. The downward visual angle will prevent 

the Pilot from seeing the lights in the first 992 feet in front of the aircraft (Figure 4-

2). With an RVR of 2400, the ground segment visible to the Pilot will be 

approximately 1,394 feet. On this approach, with the seat height properly 

adjusted, the Pilot should be able to see 1 or 2 center lead-in approach light bars. 

However, be aware that the visual segment is also a function of glide slope 

angle, glide slope transmitter location, CG, gross weight, flap setting and crab. 

Sequenced flashers and the 1,000 foot roll bar should be in sight. 

A technique to improve the downward vision angle is to use 50 flaps for the 

landing as this creates a slightly lower deck angle on final than flaps 35. 
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Further lowering results in steadily worsening visibility as in the following table: 

Seat Height Down Vision Angle

Correct 

1 inch lower 

2 inches lower 

3 inches lower

20.0°

16.5°

12.8°

 9.5°

Figure 4-1. Eye Reference Plane. 

The diagram shows that 1,506 feet of visible ground segment would be reduced to 

1,074 feet due to the pilot's seat being only one inch too low. 

2,400 200 

2,400 

1,074 

1,506 
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The effect on the visible ground segment is illustrated below: 

PILOT EYE ORIENTATION WITH GROUND 

(DISTANCES SHOWN ARE APPROXIMATED) 

FLAPS 35 (1.3 Vs)

Body angle at touchdown position (Altitude 

at 8° pitch angle, struts extended 

Figure 4-2. Visual Ground Segments Approach/Landing.

200 FT RA

NOTE: With 20° down vision, at 200 feet the pilot will have 

visual reference of 6 or 7 approach lights. 

Body angle at touchdown position (Altitude at 8°

pitch angle, struts extended) 

200 

1,394 992 

224 

2400 RVR 

231 
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5.0 LANDING ILLUSIONS

The most insidious landing illusions for a Pilot conducting a low visibility landing 

are the ones that cue him to “duck under” or dive prior to the runway. This is 

particularly hazardous for a large aircraft because the margin of safety is very 

small. A review of Figure 5-1 shows that with an ILS approach carried down to 

Runway Point of Intercept (RPI), (thus not adjusted for proper aim point and 

threshold crossing height) the actual threshold crossing height is quite low. If the 

Pilot relies entirely on visual cues and abandons his instruments and dips below 

this glide path, a landing short of the runway is a strong possibility. There are 

several influences that cue the Pilot to duck-under. Understanding these 

influences will help you resist them and rely on your instruments while 

performing a composite crosscheck of aircraft instrument and visual references. 

Approach light systems are inadequate for providing altitude cues but 

unfortunately the subconscious mind cannot always be convinced otherwise. 

We are conditioned to believe that dim lights communicate distance. But in a low 

visibility situation attributed to partial obscurity, that dim light will not be a reliable 

determination of height or distance. Thus the Pilot, upon picking up his first 

partially obscured lights, is cued to descend to get the normally bright lights he 

has been conditioned to see - the result is the classic duck-under. 

Pilots are used to establishing an aim point in the windscreen when landing. In a 

low visibility situation with only a few lights visible, the tendency is to place the 

farthest visible light as the aim point. However at 2400-foot slant range visibility 

and at 200 feet radio altimeter on a precision glide path, the farthest light visible 

will be well short of the paved surface. If the Pilot accepts this poor visual cue 

for his aim point then he will land short in a classic duck-under. 

Even in excellent visibility a Pilot may be subconsciously cued to duck-under. In 

a "black hole" approach conducted over water, using an inadequate ALS, or 

even into a very bright urban horizon where night vision may be impaired, a Pilot 

may establish a flat glide path due to the absence of visual cues in the 

foreground. This is why AFI 11-2KC-10V3 dictates that we fly the most precise 

approach available during night and marginal weather operations. Visual or VFR 

approaches conducted away from home station under these conditions require 

visual guidance to help prevent this phenomenon. 

All of these constitute a subconscious response by the Pilot that he must 

anticipate and overcome in a low-visibility landing. Proper anticipation will allow 

the Pilot to trust his instruments instead of his reactions to the visual cues he is 

receiving. 
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APPROXIMATE TOUCHDOWN POINT (NO FLARE) ASSUMING G/S 

TRANSMITTER AT 1000'

FLAPS 

(NO DLC) 

(DEGREES)

GLIDE PATH 

ANGLE 

(DEGREES)

ESTIMATED 

BODY ANGLE 

 (1) (2)

ANTENNA HEIGHT 

Ha, AT THRESHOLD

(FEET)

MAIN GEAR HEIGHT

Hg, AT THRESHOLD

 (1) (2)

MAIN GEAR TOUCH

DOWN POINT, T 

(1) (2)

50 2.5 5.7 4.7 44 14 16 326 365

35 2.5 6.7 5.7 44 13 14 287 326

50 2.75 5.45 4.45 48 19 20 387 422

35 2.75 6.45 5.45 48 17 19 352 387

50 2.5 5.2 4.2 52 23 25 438 471

35 2.5 6.2 5.2 52 21 23 405 438

(1) C.G. @ 11.6% MAC 

(2) C.G. @ 29.0% MAC 

Figure 5-1. ILS Approach.

PIL O T E YE (AN TEN NA + 7 FT) H EIG HT

AN TEN NA H EIG H T A T TH R ESH O LD

ILS G L IDE SLO P E

ILS G L IDE SLO P E AN G LE

G L ID ESL O PE TR AN SMITTER

MA IN G EAR

PA TH

MA IN G EAR

TOU CH DOW N

POINT

MA IN G EAR

H EIG HT AT

TH RES HOL D

H a

H g

T

1000 F T

AIR PLA NE B O DY A NG L E

TH RES HOL D
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6.0 TRANSITION TO VISUAL

As the Pilot approaches DH or the MAP, he must make the decision to continue the 

approach or execute a missed approach. The decision to continue the approach is not, 

however, a commitment to land. Command guidance is clear on requirements 

necessary to commence an approach and to continue the approach below minimums, 

but it is a highly subjective decision by each Pilot on what constitutes sufficient visual 

cues to land. 

Landing is a visual maneuver. Instruments can get you close, but the final flare 

maneuver is visual. Reference to Figure 5.1 shows that the consequence of maintaining 

the electronic glideslope is to cross the threshold below 50 feet. . The KC-10 landing 

gear will cross the threshold approximately 25 feet below the glideslope antenna. The 

FARs require a warning on the approach plate for Group 4 aircraft (DC-10s) if our wheel 

crossing height at the threshold is less than 20 feet. Even if the glide path were kept in 

the pilot’s crosscheck, on most runways being “on glide path” on your instruments will 

put the gear too close to the runway threshold. The Dash one states the Pilot will plan to 

cross the threshold at 50 feet and to accomplish this, the Pilot must establish an aim 

point 1500 to 1800 feet down the runway, a distinctly visual maneuver. If available, a 3-

bar VASI can help. But the far bar on a 3-bar VASI is located 2,000 feet down the 

runway and thus may not be visible during the transition to a visual aim point. In a low 

visibility approach situation, the VASI's are not much help because they are acquired 

too late, if at all, but on a VFR day, they greatly aid in flying a visual glidepath. The 

PAPI glide path angle is normally set for the type of aircraft that normally transits the 

airfield. Without information published in the airfield facility directory stating that they’re 

aligned for group 4 aircraft, it is better to fly three white an one red light than two of each 

color on final and realize that this may transition to 4 white lights the closer we get to the 

runway depending on how far down the runway the lights are positioned. Remember 

that whatever glideslope you are using, you must fly the final portion slightly high in 

order to obtain the required 50' TCH. 

What visual cues does the Pilot need to consider himself visual? To be a visual 

maneuver, two things are needed. The Pilot must first have adequate visual cues to 

project an accurate horizon, and second he must be able to establish an aim point in his 

windscreen. In both cases, he does not necessarily have to see a horizon or the 

touchdown zone, but he must be able to project it. As the Pilot trains and accomplishes 

numerous landings, his subconscious records the required cues to be able to do these 

two things. What are those visual cues? For each Pilot, they differ. What is acceptable 

for some is unacceptable for others. It is a very subjective training response and 

because it occurs at the subconscious level, in some ways, it is out of the Pilot's hands. 

As the Pilot gains more experience and time in the aircraft, his required cues may 

change as his sub-conscious learns to accept different cues. The Pilot must discover 

what cues he needs and establish limits for himself. 
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6.1 Determining Required Visibility

AFI 11-202, Volume 3, states that RVR reports (feet or equivalent meters), when 

given for a particular runway, apply to all takeoffs and landings on, and 

approaches to, the runway. Prevailing Visibility (PV) may be used when RVR is 

not reported. For circling approaches, PV shall be used. Whatever is reported, 

slant range visibility from the Pilot’s perspective may be much less. When 

cleared for, or established on a segment of the approach and the weather is 

reported or observed to be below approach minimums, the Pilot has the latitude 

to continue and attempt a landing. Therefore, within the confines of the 

regulation, each Pilot must subjectively determine what constitutes sufficient 

visual cues to accomplish a safe landing (Figure 6-1). 
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Figure 6-1. Cones of Vision - Various RVR’s and Altitudes. INNER MARKER

INNERMARKER

INNERMARKER

INNERMARKERINNERMARKER

INNERMARKER
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Although not restrictive for Air Force Pilots, Federal Aviation Regulations (FAR) 

define required flight visibility quite differently. "Flight visibility means the average 

forward horizontal distance, from the cockpit of an aircraft in flight, at which 

prominent unlighted objects may be seen and identified by day and prominent 

lighted objects may be seen and identified at night." How can a Pilot determine 

flight visibility? 

This FAR suggests the Pilot evaluate his flight visibility if he is to continue his 

approach. Without visual cues exterior to the aircraft, this is not possible, so he 

must continually assess his flight visibility on short final when he begins to 

receive visual cues. A count of the center lead in lights, taking into account 

down vision angles, could allow an analysis of flight visibility. Considering the 

workload, this may be somewhat difficult. A quicker method would be to brief a 

150 foot call. The green runway threshold lights should be in sight if the RVR 

exceeds 2400 feet. At the EGPWS 100-foot call, the first thousand feet of the 

runway would be visible if the RVR is 2400 feet. 

6.2 The Decision to Continue

Command guidance states "Do not continue the approach below minimums 

unless the aircraft is in a position to make a safe landing and the runway 

environment is in sight," (AFI 11-2-KC10, Volume 3). The Air Force provides 

further guidance on the definition of runway environment in AFI 11-202, Volume 

3, and “continuing an approach below DH/DA/MDA is not authorized until 

sufficient visual reference with the runway environment has been established 

and the aircraft is in a position to execute a safe landing. The runway 

environment consists of one or more of the following elements:. 

(a) The approach light system, except that the Pilot may not descend below 

100 feet above the touchdown zone elevation using the approach lights 

as a reference unless the red terminating bars or the red side row bars 

are also distinctly visible and identifiable. 

(b) The threshold, threshold markings or threshold lights. 

(c) The runway end identifier lights. 

(d) The visual approach slope indicator. 

(e) The touchdown zone or touchdown zone markings or touchdown zone 

lights. 

(f) The runway or runway markings. 

(g) The runway lights. 
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If at 100 feet, the only lights in sight are those described in paragraph (a), the 

crew should be aware that the flight visibility is much lower than required by the 

approach and if the decision is made to land it should be done with caution. The 

red terminating bars are 200 feet short of the threshold lights. Reference to 

figure 6-1 shows that this would equate to less than a 1200 foot RVR. 

6.3 Transition

The transition from instrument flight to visual flight is a challenging one. During 

this time, the Pilot must transition from a pure instrument crosscheck to a visual 

crosscheck. During that transition, he must combine elements of both into a 

composite crosscheck. Crew coordination can be critical to support the Pilot 

during the landing. AFMAN 11-217, Volume 1, suggests three techniques to 

assist the Pilot. In the first case the copilot would fly the approach and make 

required callouts while the other pilot looks for visual cues and either directs a 

go-around or takes the aircraft for landing. A second technique is to have one 

pilot fly the approach all the way to landing, while the pilot monitoring stays on 

instruments and provides inputs to help the PF avoid a duck-under. The autopilot 

is used in the third technique to a point where a go-around is accomplished or it 

is disconnected for landing. 

The approach and runway light systems are designed to help the Pilot align with 

the runway and then project an aim point and a horizon, but are unacceptable for 

establishing vertical guidance. Visual glide slope systems are designed for 

relatively good visibility conditions. They are ineffective close in and in the case 

of the far bar on a 3-bar VASI which is displaced 2,000 feet from the threshold, 

may not be seen in low visibility. 

Therefore, the most important instruments to crosscheck during a low visibility 

landing are the ones that provide vertical guidance. When practicing low visibility 

landings, it is imperative that you monitor your radio altimeter, altimeter, VSI, and 

if available, the ILS glide slope. As a technique, you may consider coordinating 

specific crew callouts if parameters you have established are exceeded. For 

example, you may brief the Pilot monitoring the landing to callout variations to 

your calculated descent rates in excess of 200 fpm low or 500 fpm high. This will 

protect you from visual illusions that cue you to duck-under the appropriate glide 

path. You may also brief the Boom Operator to look for specific visual cues and 

make appropriate call outs when the EGPWS states "100 feet;" thereby, 

monitoring your vertical descent with respect to the runway. 
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7.0 LANDING FROM PRECISION APPROACHES 

Precision approaches match up well with Approach Light Systems (ALS). Where 

even a well-designed ALS is ineffective in providing vertical guidance, precision 

approaches provide it with glide slope information. Understanding the accuracy 

of both course and glide slope (Figure 7.1) information is critical in analyzing and 

incorporating this information into a composite crosscheck. When flying a PAR, 

controller information is provided to touchdown, making a PAR very effective 

during transition to a visual landing. 

Although the KC-10 is restricted to Category I (CAT I) precision approaches, it is 

important to understand the capabilities of CAT II qualified ground equipment. 

CAT I precision approaches can be designed to be flown to 200 feet above the 

highest elevation in the touchdown zone with visibility as low as 1800 feet RVR. 

Category II can be flown down to 100 feet above with visibility as low as 1200 

feet RVR. 

The choice to continue at the decision height must be made based on the 

instrument indications and visual cues. If you are in a position to make a normal 

landing and you have the runway environment in sight you may continue the 

approach, but it does not commit you to land. If you break out at 200 feet and 

you need considerable maneuvering to align with the runway - you are not in the 

"Slot", and that will necessitate a missed approach. You certainly don't want to 

start banking the aircraft to line up with the runway when you're only a few feet 

off the ground. Putting a wingtip in the dirt will ruin your day. You should 

establish criteria to continue based on very little maneuvering required to 

stabilize for landing. A precise approach is required if you are going to land with 

weather conditions at minimums. 
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Figure 7-1. ILS Characteristics. 
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7.1 Precision Approach Radar (PAR) 

A PAR is designed to be used as a landing aid, rather than an aid for sequencing 

and spacing of aircraft. A PAR may be used as a primary landing aid, or it may 

be used for monitoring other types of approaches. It is designed to display 

range, azimuth and elevation information. 

The radar system uses a two-antenna array, one for scanning a vertical plane, 

and the other for scanning horizontally. Since the range is limited to 10 miles, 

azimuth to 20, and elevation to 7, only the final approach course area is covered. 

Normally, the Airport Surveillance Radar (ASR) provides radar vectors to the 

final approach course. The PAR radarscope is divided into two parts. The upper 

half presents altitude and distance information, and the lower half presents 

azimuth and distance. 

A PAR is one in which a controller provides highly accurate navigational 

guidance in azimuth and elevation to the Pilot. Pilots are given headings to fly, 

to direct them to, and keep their aircraft aligned with the extended centerline of 

the landing runway. They are told to anticipate glide path interception 

approximately 10 to 30 seconds before it occurs and when to start descent. The 

published Decision Height will be given only if the Pilot requests it. If the aircraft 

is observed to deviate above or below the glide path or left or right of centerline, 

the Pilot is given the relative amount of deviation by use of terms "slightly" or 

"well" and is expected to adjust the aircraft's heading/vertical speed as 

necessary to return to the glide path or centerline. Range from touchdown is 

given at least once each mile. If an aircraft is observed by the controller to 

proceed outside of specified safety zone limits in azimuth and/or elevation and 

continue to operate outside these prescribed limits, the Pilot will be directed to 

execute a missed approach or to fly a specified course unless the Pilot has the 

runway environment (runway, approach lights, etc.) in sight. 

7.2 Instrument Landing System (ILS) 

The ILS consists of two highly directional transmitting systems that provide 

localizer and glide slope guidance (Figure 7-1). For CAT II operations, FAA 

specifications call for a minimum amount of variation in signal strength. They 

also call for minimum interference to the transmitted signals from outside 

sources. 

LOCALIZER. The localizer signal is adjusted between 3 and 6 degrees to 

provide a linear width of 700 feet at the runway threshold. During CAT II 

operations, ILS critical areas are kept clear of surface traffic to prevent signal 

interference. Figure 7-2 shows the localizer and glideslope critical areas. 

GLIDESLOPE. The glide slope transmitter provides guidance in the vertical 

plane and radiates its signal principally in the direction of the approach. Any 

instrument indications of a glide path other than those within the width of the 

localizer course should be disregarded. For CAT II operations, the optimum glide 
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slope threshold crossing height of the receiving antennae is 50 feet. The 

maximum is 60 feet and a height as low as 47 feet may be used at some 

locations. This threshold crossing height normally requires a glide slope angle of 

2.75 to 3.0 degrees. The Category II ILS glideslope becomes a hyperbolic curve 

at approximately 100 feet and flares 18 to 27 feet in the air. Figure 7-2 shows 

the glide slope critical area. 

MARKER BEACONS - In addition to the outer marker (OM) and the middle 

marker (MM), an inner marker (IM), is provided at each CAT II runway. It is 

located almost directly below the 100-foot decision point. Aural identification is 

six "dits" per second and visual identification is on the white inner marker beacon 

light. The marker beacons provide information only and are not required for the 

approach. 
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NOTE: 

1. Location of hold lines when operations are permitted on a 400' parallel 

taxiway. 

2. Or to the end of the runway, whichever is greater. 

Figure 7-2. CAT II Critical Areas.
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8.0 LANDING FROM NON-PRECISION APPROACHES

The weaknesses of the approach light system (ALS) are minimized during a 

precision approach but they are amplified during a non-precision approach. An 

ALS provides poor vertical guidance and a non-precision approach provides 

none. To aggravate the situation, non-precision course guidance can be very 

imprecise depending on location of the navigation aid providing final approach 

course guidance. Also, a non-precision can still qualify as a straight-in approach 

if the course is as much as 30 degrees off of the runway heading. This requires 

the Pilot to do significant maneuvering while trying to perform a controlled 

descent to landing. 

To land successfully from the non-precision approach requires significantly more 

planning than the precision approach. The Pilot must anticipate where his first 

visual cues will appear in his windscreen. The Pilot's first cues may even be 

seen in a side window if the course is 30 degrees off runway heading and is 

amplified by the effects of crosswinds. Without anticipation of where his visual 

cues will appear, the Pilot may not acquire the field visually. 

The Pilot must strive to fly accurate final approach courses. Even one degree of 

error from the prescribed course may make it impossible for the Pilot to acquire 

the runway environment and maneuver to land. As an example, analyze the 

TACAN approach to runway 3L at Travis AFB (Figure 8-1). Using the 60-1 rule 

shows that for every degree off course at 1 NM represents 100 feet. One degree 

off course at the TACAN VDP is 290 feet. 

The necessary cues the Pilot needs to continue the approach below MDA may 

also increase. If the Pilot must maneuver the aircraft significantly, he must 

acquire significantly more visual cues to enable him to project a horizon sooner 

than on other approaches. Runway alignment may be difficult if the runway has 

a poor or non-existent Approach Lighting System. With the localizer portion of a 

published ILS being the notable exception, navigation aids will not be useful for 

alignment once departing the MDA. The Pilot should give careful consideration 

to departing the MDA with only a few cues available. There must be enough 

cues available to find an aim point and project a horizon. You cannot properly 

evaluate a visual glide path without the ability to project a horizon. The Pilot 

must consider himself visual before departing the MDA. 

Under these conditions, the Pilot should set higher standards for what constitutes 

the runway environment for continuing on a non-precision versus a precision 

approach. From the higher altitudes of an MDA the Pilot has a better chance of 

seeing the VASI's for cross-checking the visual glidepath. 

Without electronic or visual glide path information, the descent must be well 

planned. Most Controlled Flight into Terrain (CFIT) accidents occur on nonprecision approaches and of those, vertical navigation errors is the primary 

cause. An inflight determination of acceptable visibility to conduct a visual 
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descent from MDA must be considered. A VDP and descent rate should be 

calculated. Recognize that when the decision to continue the approach below 

the MDA is made the Pilot must immediately transition from level flight to a glide 

path. Without a horizon to establish a controlled pitch change, the Pilot must 

estimate the initial pitch change on the ADI. This may generate visual illusions 

that must be controlled and a composite crosscheck to verify proper descent 

rates. Crew actions should be coordinated to ensure a proper descent rate. The 

Pilot must acquire an aim point as soon as possible in order to verify and adjust 

the glide path. 

Both the alignment maneuver and the descent must be accomplished 

immediately. The Pilot should accept that he needs many visual cues to 

simultaneously project a horizon, acquire an aim point, and safely maneuver the 

aircraft to align with the runway. The Pilot must develop a sense of what is 

acceptable through practice in the simulator. 
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Figure 8-1.
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9.0 AFTER TOUCHDOWN CONSIDERATIONS 

Main gear touchdown does not relieve the Pilot of all the challenges of operating 

in low visibility conditions. Reported visibility for your approach and actual 

conditions may differ. Even the reported RVR, as measured from the approach 

end transmissometer, does not report what you actually see. It measures 

visibility to the side of the runway and 12 to 16 feet above the approach end of 

the runway. RVR measured at the departure end is advisory only and may be 

significantly worse than the approach end visibility. At touchdown the Pilot's eye 

position is at 36 feet and after lowering the nose is still at 20 feet. All of this 

contributes to potential challenges. The approach and landing is not complete 

until the aircraft is slowed to a taxi speed and ready to turn off the runway. 

Recognizing the potential challenges after landing stresses the importance of 

landing on speed, on centerline, in the touchdown zone and on runway heading if 

in a crosswind. After a stable beginning, the Pilot can better predict his position 

and the level of braking necessary to stop the aircraft. If in doubt, maximum 

braking should be applied. Remember that braking is poor on wet rubber 

deposits in the vicinity of touchdown zones. 

After touchdown there are other visual cues to aid the Pilot in determining his 

relative position on the runway. If installed, TDZ Lighting ends at 3,000 feet, 

cuing the Pilot to whether the landing was too long. Runway edge lights 

communicate caution beginning at 2,000 foot remaining and, if installed, the 

centerline lights give additional warnings at 3,000 and 1,000 feet remaining. 

Again, careful planning and crew briefings will alert the Pilot and crew as to what 

visual guidance exist to help determine your location on the runway during 

rollout. 

Even taxiing on the ramp can be hazardous as ramp lighting systems are highly 

non-standard. As an example, some airfields provide centerline blue taxi lights. 

Air Force ramps and taxiways use blue lights only for edge lighting. Confusion 

over taxi lights can lead to taxi accidents or runway incursions. 
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10.0 SUMMARY

Prior to landing in Low Visibility conditions, while still at altitude, the crew should 

be thoroughly briefed on the approach and what to expect. Approach lighting 

system, runway lighting, runway markings and runway length and width should 

be reviewed. Emphasis on appropriate call outs will help the Pilot determine his 

position and altitude relative to the runway. Every crewmember should be 

actively involved in monitoring the approach and landing. 

This workbook has emphasized that the decision processes pertaining to low 

visibility landings are highly subjective. Every Pilot must develop his own 

personal criteria for continuing an approach and landing. Regulatory guidance 

reflects this as well. Therefore, this workbook provides few hard and fast 

answers to the challenges every Pilot will face. But, it can help you to define the 

challenges, thus allowing you to anticipate the problems and perhaps allow good 

CRM to overcome them. Preparation and practice coordinating crew efforts in 

the simulator, in trying conditions, will give you the confidence to succeed in 

actual conditions. In day-to-day operations, crewmembers can be trained to 

scan for specific visual cues and to use standardized terminology in mandatory 

call outs, thus preparing them for an encounter with challenging conditions. The 

following section suggests activities you can practice in the simulator to help you 

prepare for that challenging Low Visibility approach. 

10.1 Suggested Simulator Exercises 

The following activities are suggested to help the crew gain experience in and 

anticipate the challenges of low-visibility approaches and landings. Weather 

conditions and visibility are set slightly above minimums for the approaches. 

1. On a precision approach, with a strong headwind, and a 275,000 # gross 

weight, fly a 35/Ext approach to a DH and select position freeze. Vary 

aircraft configuration, CG, crosswinds, visibility and Approach Lighting 

System models. Select snapshot take and reposition the aircraft to fly 

several approaches and landings. Increase gross weight to 432,000# with 

a 0/Ret configuration; change the strong headwind to a 5-knot tailwind and 

release. Challenge the crew to call out visual references, using 

standardized terminology, during the approach at this increased airspeed. 

2. Repeat the process for a non-precision approach. Demonstrate visual 

references at both the VDP and MAP. Also observe changes in the visual 

picture as the aircraft transitions from level flight to a glide path. Select an 

approach with the final approach guidance not aligned with the runway 

and adjust crosswinds to move the view even further from the center of 

the windscreen. The TACAN Approach to Runway 6 at McGuire AFB or 

the TACAN Approach to Runway 3L at Travis AFB are good examples. 
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Put in a strong North wind and the drift correction will put the runway far 

right of center in the windscreen. 

3. Adjust minimums for ALS inoperative and fly approaches without 

approach lighting.