AFS-12-325-E

Exemption No. 11609

UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

WASHINGTON, DC 20591

 

In the matter of the petition of 

 

BERRY AVIATION, INC. Regulatory Docket No. FAA-2012- 0444

 

for an exemption from

§ 135.181(a)(2) 

of Title 14, Code of 

Federal Regulations 

GRANT OF EXEMPTION

 By letter dated April 17, 2012, Mr. Stanley Finch, Director of Operations, Berry Aviation, 

Inc. (BAI), 1807 Airport Drive, San Marcos, TX 78666, petitioned the Federal Aviation 

Administration (FAA) on behalf of Berry Aviation for an exemption from § 135.181 (a)(2) of 

Title 14, Code of Federal Regulations (14 CFR). The proposed exemption, if granted, would

allow BAI to operate its Dornier Do328-100 series (Do328) and its Bombardier DHC-8-

100/200 series (DHC-8) of aircraft for passenger carrying under visual flight rules (VFR)

over-the-top or under instrument flight rules (IFR) conditions at a weight that will not allow it 

to climb with the critical engine inoperative, at least 50 feet a minute, when operated at the 

minimum enroute altitudes (MEAs) of the route to be flown or 5,000 feet mean sea level 

(MSL), whichever is higher.

The petitioner requests relief from the following regulation:

Section 135.181 (a)(2), prescribes, in pertinent part, that no person may operate a 

multiengine aircraft carrying passengers over-the-top or in IFR conditions at a weight 

that will not allow it to climb, with the critical engine inoperative, at least 50 feet a 

minute when operating at the MEAs of the route to be flown or 5,000 feet MSL, 

whichever is higher.

The petitioner supports its request with the following information:
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BAI states the Do328 and DHC-8 are certificated in accordance with 14 CFR part 25 and have 

maximum certificated takeoff weights well in excess of 12,500 pounds. Both aircraft types are 

turbine powered and are thus considered “large turbine powered transport category” aircraft. 

Large turbine powered transport category aircraft operated in accordance with 14 CFR part

135 are subject to two separate and distinct en route performance requirements:

A. Section135.181 (a) applies to all aircraft operated over-the-top or in IFR conditions. It

states, in part, (a) Except as provided in paragraphs (b) and (c) of this section, no 

person may-

(1) Operate a single-engine aircraft carrying passengers over-the-top; or 

(2) Operate a multiengine aircraft carrying passengers over-the-top or in IFR 

conditions at a weight that will not allow it to climb, with the critical engine 

inoperative, at least 50 feet a minute when operating at the MEAs of the route to be 

flown or 5,000 feet MSL, whichever is higher.

B. Section 135.381(a), titled Large transport category airplanes: Turbine engine powered: 

En route limitations: One engine inoperative, states that no person operating a turbine 

engine powered large transport category airplane may take off that airplane at a weight,

allowing for normal consumption of fuel and oil, that is greater than that which (under 

the approved, one engine inoperative, en route net flight path data in the Airplane 

Flight Manual for that airplane) will allow compliance with paragraph (a) (1) or (2) of 

this section, based on the ambient temperatures expected en route.

(1) There is a positive slope at an altitude of at least 1,000 feet above all terrain and 

obstructions within five statute miles on each side of the intended track, and, in 

addition, if that airplane was certificated after August 29, 1958 (SR422B), there is 

a positive slope at 1,500 feet above the airport where the airplane is assumed to 

land after an engine fails.

(2) The net flight path allows the airplane to continue flight from the cruising altitude 

to an airport where a landing can be made under §135.387 clearing all terrain and 

obstructions within five statute miles of the intended track by at least 2,000 feet 

vertically and with a positive slope at 1,000 feet above the airport where the 

airplane lands after an engine fails, or, if that airplane was certificated after 

September 30, 1958 (SR422A, 422B), with a positive slope at 1,500 feet above the 

airport where the airplane lands after an engine fails.

Aircraft operated under 14 CFR part 135 are subject to numerous performance requirements 

that include takeoff, landing, and the en route performance limits described above. When the 

route of flight must traverse an area that includes high terrain, en route performance is often 

the most limiting factor and can lead to significant reductions in maximum permissible 

takeoff weight.
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The petitioner also stated the enroute performance requirements of §§ 135.181(a)(2) and 

135.381(a)(2) are very similar in that both rules require the aircraft to maintain a safe altitude 

with one engine inoperative. Section 135.181(a)(2) requires all multi-engine airplanes to be 

capable of climbing higher than either the MEA over which the aircraft will be flown or 5,000 

MSL, while § 135.381 permits the operator to choose between § 135.381(a)(1) and 

§ 135.381(a)(2), the latter of which is commonly known as “driftdown.” Using an en route 

performance limit based upon § 135.381(a)(2), qualified driftdown procedures, instead of 

§§ 135.181(a)(2) or 135.381(a)(1) permits the aircraft to takeoff at a substantially higher gross 

weight, thus permitting a greater payload. Because of the complexities of computing 

driftdown performance in accordance with § 135.381(a)(2), the FAA requires air carriers to 

obtain approval of their procedures in the form of Operations Specification (OpSpec) B029 

prior to employing driftdown performance procedures. Pursuant to this end, BAI has obtained 

approval of its driftdown procedures used to comply with § 135.381(a)(2) via OpSpec B029.

BAI therefore seeks relief from § 135.181(a)(2) in order to carry greater payloads over certain 

routes, particularly routes over high terrain, by meeting en route performance requirements 

established by § 135.381(a)(2).

Benefit to Public

The impetus for this petition is the flight operations conducted by BAI in Afghanistan on 

behalf of the United States Department of Defense. BAI currently has one 30-passenger 

Do328 based at Kabul International Airport (OAKB) supporting the United States Central 

Command (CENTCOM) counter narcotics and three 21-passenger DHC-8s based at Bagram 

Air Base (OAIX) on contract to the United States Transportation Command 

(USTRANSCOM). The minimum en route altitudes in Afghanistan and the surrounding 

countries are very high, sometimes exceeding 20,000 feet MSL in the Hindu Cush mountain 

region. Grant of this petition will benefit the public by permitting the safe transport of more 

personnel and baggage on a single flight, thus reducing the number of flights required. The 

benefit increases greatly during times of higher temperatures due to the negative impact of the 

resulting higher density altitudes on single engine en route performance.

Impact on Safety

Grant of this exemption will not adversely impact the safety of BAI's flight operations. The 

operating rule that affords the highest level of safety among U.S. operating rules is part 121.

The en route performance requirements of § 135.381 are identical to those of § 121.191. BAI 

thus proposes to be exempt from a requirement that has no counterpart in part 121 and to 

comply fully with an en route performance rule identical to § 121.191. As noted earlier, BAI 

has already obtained approval for its method of compliance with § 135.381(a)(2) driftdown 

procedures via OpSpec B029.
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Request to Not Publish

BAI requests a waiver of the 120 day filing requirement and requests that this petition not be 

published in the Federal Register since a grant will not set precedence. Examination of the 

FAA's Automated Exemption System (AES) indicates the grant of several similar petitions, 

most of which are outdated and were originally granted to air carriers operating turboprops 

that performed scheduled passenger service prior to moving such operations from part 135 to

part 121. In addition, FAA Order 8900.1 Volume 4, Chapter 3, Section 1, Paragraph 4-500E, 

states “part 135 operators may apply for a grant of exemption to use driftdown or fuel 

dumping as an alternate means of compliance with §§ 135.181 or 135.183 in accordance with 

part 11, which further indicates that the FAA anticipates petitions for exemption.

Request to Operate Under Exemption Outside United States

Though the impetus for the petition was the operations conducted by BAI in Afghanistan, BAI 

strongly prefers that grant of this petition includes operations conducted inside and outside the 

United States. Further, BAI requests that consideration of grant of this petition not be limited 

solely to operations conducted in Afghanistan. The methodology that BAI developed for 

compliance with driftdown performance and approved via OpSpec B029 may be applied to 

any route within BAI's approved area of operations.

International Civil Aviation Organization (ICAO) Annex 6, Part 1, Attachment C, Example 1, 

and specifically paragraph 4.1.2 permits driftdown as a method of compliance with en route 

performance limitations, and the United States does not have a difference filed with ICAO

concerning en route performance limitations. Approval to operate under this exemption 

outside the United States will not require filing a difference with ICAO.

The FAA has determined that good cause exists for waiving the requirement for Federal 

Register publication because the exemption, if granted, would not set a precedent and any 

delay in acting on this petition would be detrimental to BAI.

The FAA's analysis is as follows:

Section 135.181(a)(2) sets limitations on passenger carrying, over-the-top flights for the 

purpose of ensuring that these flights maintain a safe altitude with one engine operative. As 

part of its research and analysis, the FAA considered the following: the routes and areas over 

which the petitioner currently operates, the performance capabilities of its aircraft, the 

accuracy of the driftdown data and the procedures BAI will follow for planning flights and in 

reacting to an unscheduled shutdown of one engine while flying over routes and intended 

areas of operation, and the efficacy of the operator’s driftdown procedures and training 

program. Given the routes to be flown combined with the driftdown procedures, the FAA 

finds that BAI aircraft, when operated in accordance with procedures and approved data 

reviewed by the FAA during the approval process for OpSpec B029, should be able to 

maintain obstacle clearance in the event of an unscheduled engine shutdown. Furthermore, 

the FAA finds that granting this petition allowing BAI to use driftdown procedures with the 

larger aircraft will permit higher payloads without compromising safety, thus reducing the 
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number of flights and exposure to the hostile terrain. Based on these findings, the FAA has 

determined that a grant of exemption is in the public interest and will provide a level of safety 

at least equivalent to the rule from which the exemption is sought.

The petitioner states that the impetus for this petition is the flight operations conducted by 

BAI in Afghanistan on behalf of the United States Department of Defense and that the 

minimum en route altitudes in Afghanistan and the surrounding countries are very high, 

sometimes exceeding 20,000 feet MSL in the Hindu Cush mountain region. The FAA finds 

that the terrain within the area where these flight operations are proposed is sufficiently 

mountainous to preclude alternative routes. 

The petitioner’s driftdown procedures have been approved by the FAA through the issuance 

of OpSpec B029. The FAA finds that the one engine inoperative performance capabilities of 

the Do328 and the DHC-8 aircraft are sufficiently robust to successfully execute the driftdown 

procedures from any point in the en route portion of the flight, given that: (1) the flight is 

conducted in accordance with approved pre-takeoff calculations of driftdown profiles and 

minimum cruise altitudes and that and (2) actual environmental parameters (wind and 

temperature) encountered at the proposed cruise altitude support the pre-takeoff calculations 

predicting sufficient driftdown performance for the aircraft weight and altitude.

The FAA notes that performance calculations are well documented and along with 

performance data, are taken from FAA and manufacturer approved aircraft flight manuals for 

both the D0328 and the DHC-8. The FAA has already approved BAI driftdown calculations 

and procedures based upon these aircraft flight manuals via OpSpec B029. BAI flight crew 

and operational control personnel use approved data and procedures to calculate and verify 

driftdown profiles, minimum cruise altitudes, and route planning to suitable diversionary 

airports. When the aircraft performance calculations predict adequate driftdown profile 

performance and the aircraft is flown in accordance with these performance calculations, 

preflight planned diversion routes, and driftdown procedures, the safety of flight is not 

compromised in the event of an unscheduled engine shutdown during the enroute phase of the 

flight.

The FAA highlights that suitable diversion airports must be available in sufficient number and 

in appropriate locations to support safe driftdown profiles and routes from any point along the 

intended primary route, to facilitate safe approach and safe landing after suffering an 

unscheduled engine shutdown and implementation of driftdown procedures.

The FAA finds that the FAA-approved BAI pilot training program covers contingency flight 

planning and verification methods and standardized communication to the flight crew of the 

following information: maximum weights, minimum flight altitudes, mandatory crossing 

altitudes, appropriate diversionary airports for all route segments, and driftdown procedures / 

parameters. The operational control personnel and flight crews must receive training and 

checking regarding the methods, procedures, and software applications to be used.
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In summation, the capability of the aircraft, the availablility of manufacturer-approved and 

published performance data and performance calculation methods, and BAI driftdown policies 

and procedures, combined with the provision of appropriate training of flight crew and 

operational control personnel, facilitate application of driftdown techniques. These techniques 

enhance the overall safety of each flight while enabling higher payloads, which in turn reduces 

the number of flights required. This improvement in efficiency and reduction in risk are both 

in the public interest.

The FAA’s Decision

In consideration of the foregoing, I find that a grant of exemption is in the public interest and 

will not adversely affect safety. Therefore, pursuant to the authority contained 

in 49 U.S.C. §§ 106(f), 40113 and 44701, delegated to me by the Administrator, Berry 

Aviation, Inc. is granted an exemption from § 135.181(a)(2) to the extent necessary to allow 

Berry Aviation, Inc. to operate its Do328 and DHC-8 aircraft for passenger carrying under 

VFR over-the-top or under IFR at an altitude that will allow driftdown over a pre-planned 

descent profile to a safe landing using the routes that have been determined by using the 

manufacturer’s approved performance data and meteorological reports and forecasts obtained 

prior to flight. This exemption is subject to the following conditions and limitations:

Conditions and Limitations

1. This exemption is applicable only to the Do328-100 series (Do328) and Bombardier 

DHC-8-100/200 series (DHC-8) aircraft as approved on Operations Specification 

paragraph D085 for the air carrier. 

2. When operating outside of the United States, this exemption does not relieve the 

certificate holder or the flightcrew from compliance with any contrary nation state or 

ICAO regulations. 

3. Before approving the driftdown procedures, the Certificate Holding District Office 

(CHDO) will review the operator’s procedures for analyzing the weather reports and 

forecasts, the route, route segment, or area concerned, and the methods for calculating 

aircraft performance given current conditions. Driftdown parameters must be made 

available to the pilot in command (PIC) to calculate route segments and diversion 

plans. Special emphasis should be applied to —

a. Minimum obstruction clearance altitudes and minimum IFR air carrier terrain 

clearance altitudes;

b. Routes from any point on any route segment to suitable one engine inoperative 

diversion airports;

c. Current and forecast weather including temperatures and winds aloft and icing 

conditions for en route, destination, and alternate / diversion airports;
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d. Navigation aids availability and reception altitudes;

e. Air Traffic Control (ATC) availability, frequencies, loss of two way 

communication and diversion procedure coordination;

f. Available approaches;

g. Aircraft performance vs. missed approach / obstacle departure procedure 

requirements for one engine inoperative at diversion airport;

h. Runway lengths, widths, and orientations; and

i. Airport fire fighting, rescue resources, and medical facilities.

 

4. The certificate holder must make the following information available to the flightcrew

prior to take-off —

a. Approved winds and temperatures aloft forecasts along the route of flight and 

within the vicinity of any diversion route;

b. At least one suitable diversionary airport within the calculated driftdown profile 

for each route segment. (For the purposes of this exemption, suitable is defined as 

having sufficient runway length, width, condition, and orientation with respect to 

wind, available required emergency services, a weather forecast from an approved 

source indicating the airport will remain above IFR alternate weather minimums, 

and if the airport is forecast to be less than VFR, missed approach obstacle 

clearance planes shallow enough to accommodate a missed approach executed by 

the diverting aircraft with the critical engine inoperative.);

c. The prevailing and forecast weather conditions, particularly weather data necessary 

for the assessment of the effect of icing conditions on aircraft driftdown 

performance and the ceilings and visibility at all potential suitable diversionary 

airports;

d. The kinds, locations, and service volumes of available surface navigation aids;

e. If GPS capability is required for safe driftdown diversion enroute and terminal 

navigation, Receiver Autonomous Integrity Monitoring (RAIM) availability for

global positioning satellite (GPS) navigation from any point along the primary 

route to all suitable diversionary airports is verified prior to departure; 

f. Significant terrain features, such as mountains and obstructionswithin the vicinity 

of the planned primary route and diversion routes; 

g. Air traffic control considerations, such as communication processes, decisions, 

coordination, and IFR procedures;

h. Availability of a departure alternate airport in case of engine failure during or after 

takeoff, and prior to entering the enroute phase of the flight;
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i. In addition to requirements contained in §§ 135.89 and 135.157, the aircraft must 

be equipped with sufficient emergency oxygen resources to continuously supply 

the pilots and passengers when flying on the primary and diversionary route 

segments, until descending to an appropriate altitude; and

j. Any other operational factors that may affect the successful completion of a 

driftdown diversion following loss of power from one engine.

5. Berry Aviation shall maintain and utilize only OpSpec B029 approved procedures to 

ensure that, in the event of failure of the critical engine, the performance capabilities of 

its applicable aircraft (Do328 & DHC-8) will permit driftdown from the cruising 

altitude to a flight altitude not below a safe predetermined altitude on the pre-planned 

safe escape route of flight. BAI will have determined, immediately prior to each 

flight, a driftdown profile and safe escape routes along all route segments of each

flight that will ensure safe terrain clearance margins and safe landing of the aircraft at

a suitable airfield. These procedures must be approved by the CHDO. 

6. Prior to filing a flight plan on the route segments, the PIC shall determine the lowest 

cruise altitude to ensure compliance with Condition No. 4 above. The rate of descent 

and cruise speed used in accordance with the approved driftdown procedure for the 

Do328 and DHC-8 aircraft operating over approved routes with the critical engine 

inoperative will be determined by the pilot using current and forecast weather and 

approved performance data by complying with the operator’s accepted procedures for 

engine failure while en route. When operations are to be conducted in actual or 

forecast icing conditions, the driftdown calculations must include the performance 

degradation associated with “Anti-ice ON.”

7. If the weather conditions at the departure airport or at required diversionary airports 

are currently or forecast to be below landing minimums, the aircraft is not authorized 

to depart until a safe return landing can be assured and the weather conditions at either 

the departure airport, a suitable takeoff alternate airport within 1 hour flight time, or at 

any required diversionary airports along the route are at or above landing minimums. 

8. The BAI operations manual system must be revised to include approved driftdown 

procedures, and its approved training program must be amended to contain provisions 

for driftdown operations. The flight crew members and operational control personnel 

must be trained in accordance with these policies and procedures prior to exercising 

the privileges of this exemption. Additionally, the approved training program and 

company operations manual shall specifically emphasize that driftdown performance is

based on compliance with the operator’s accepted procedures for en route engine 

failure. 
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This exemption terminates on June 30, 2017, unless sooner superseded or rescinded.

Issued in Washington, DC, on May 13, 2015.

/s/ 

John Barbagallo

Deputy Director , Flight Standards Service .