DEPARTMENT OF THE AIR FORCE

HEADQUARTERS AIR FORCE FLIGHT STANDARDS AGENCY 

11 May 15

MEMORANDUM FOR HQ FAA/AGC-10

FROM: HQ AFFSA/XOF

 6500 South MacArthur Blvd, Bldg 4

 Oklahoma City, OK 73169

SUBJECT: 14 CFR Exemption 4371 Renewal (Regulatory Docket FAA-2000-8093)

1. FAA Exemption 4371 was granted to the United States Air Force on 21 Jun 85; as amended 

to 4371M on 19 April 2013, it exempts USAF aircraft from the provisions of Title 14, Code of 

Federal Regulations § 91.177(a)(2) and 91.179(b)(1). The requirement for USAF aircraft to 

conduct low-level operations without complying with en route minimum altitudes for flight 

under instrument flight rules (IFR) or direction of flight requirements for IFR en route segments 

in uncontrolled airspace has changed. 

2. Due to technological advances in aircraft systems, as well as current and future operational 

requirements, the Air Force needs to train aircrew and employ aircraft at altitudes lower and 

distances longer than granted in the current exemption. Military Training Route (MTR) 

operations are not governed by this exemption since their operations are covered in FAAO 

7610.4. The Air Force requests the following amendments to 4371M:

a. All aircraft operating within Special Use Airspace (SUA):

i. May fly as low as the bottom of the SUA floor when authorized by the 

appropriate military authority.

b. Fixed-Wing Aircraft operating IFR outside SUA or MTRs:

i. Minimum altitude when employing Terrain Following/Terrain Avoidance 

(TF/TA) procedures will be no lower than 200 feet Set Clearance Plane 

(SCP).

ii. Minimum altitude when employing visual low-level procedures will be no 

lower than 100 feet above obstacles.

c. Rotary-Wing Aircraft operating IFR outside SUA or MTRs:

i. Minimum altitude when employing TF/TA procedures will be no lower than 

100 feet SCP.

ii. Minimum altitude when employing visual low-level procedures will be no 

lower than 50 feet above obstacles.

d. Tilt-Rotor Aircraft operating IFR outside SUA or MTRs:

i. Minimum altitude when employing TF/TA procedures will be no lower than 

100 feet SCP.
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ii. Minimum altitude when employing visual low-level procedures in “Airplane” 

mode will be no lower than 100 feet above obstacles.

iii. Minimum altitude when employing visual low-level procedures in 

“Conversion” mode will be no lower than 50 feet above obstacles.

e. All aircraft operating IFR outside SUA or MTRs under this exemption are limited to a 

maximum route length of 240NM. 

3. Safety will be ensured during all of the above military operations through a combination of 

airframe technology and mission planning. The proper military authority will limit operations by

airframe based upon capabilities (i.e. TF/TA set performance, operating low-level airspeeds, etc.) 

and mission requirements. A large number of military airframes must train to low-level 

operations to accomplish their mission-set and it is therefore imperative for them to perform lowlevel IFR operations below 1000 feet.

4. If this exemption is not granted, it will cause hardship for a large number of USAF aircraft

across multiple MAJCOMs. All training for IFR low-level operations will be forced to occur in 

MTRs, increasing MTR workload as well as increasing chances of flight-path deconfliction 

challenges. Safety could be negatively impacted and critical training for contingency operations 

will be lost.

5. Please contact me at (405) 582-6087 or hqaffsa.xof@us.af.mil if there are any questions or

concerns. Thank you in advance for your assistance.

5/11/2015

X

ANDREW B. KREBS, Maj, USAF

Assistant Chief, Flight Directives Division

Signed by: KREBS.ANDREW.B.1232714219