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AIM

10/12/17

6−4−1

Two-way Radio Communications Failure

Section 4. Two-way Radio Communications Failure

6−4−1. Two-way Radio Communications

Failure

a. It is virtually impossible to provide regulations

and procedures applicable to all possible situations

associated with two-way radio communications

failure. During two-way radio communications

failure, when confronted by a situation not covered in

the regulation, pilots are expected to exercise good

judgment in whatever action they elect to take.

Should the situation so dictate they should not be

reluctant to use the emergency action contained in

14 CFR Section 91.3(b).

b. Whether two-way communications failure

constitutes an emergency depends on the circum-

stances, and in any event, it is a determination made

by the pilot. 14 CFR Section 91.3(b) authorizes a

pilot to deviate from any rule in Subparts A and B to

the extent required to meet an emergency.

c. In the event of two-way radio communications

failure, ATC service will be provided on the basis that

the pilot is operating in accordance with 14 CFR

Section 91.185. A pilot experiencing two-way

communications failure should (unless emergency

authority is exercised) comply with 14 CFR

Section 91.185 quoted below:

1. General. Unless otherwise authorized by

ATC, each pilot who has two-way radio communica-

tions failure when operating under IFR must comply

with the rules of this section.

2. VFR conditions. If the failure occurs in

VFR conditions, or if VFR conditions are encoun-

tered after the failure, each pilot must continue the

flight under VFR and land as soon as practicable.

NOTE−

This procedure also applies when two-way radio failure

occurs while operating in Class A airspace. The primary
objective of this provision in 

14 CFR Section

91.185 is to

preclude extended IFR operation by these aircraft within

the ATC system. Pilots should recognize that operation

under these conditions may unnecessarily as well as

adversely affect other users of the airspace, since ATC may

be required to reroute or delay other users in order to

protect the failure aircraft. However, it is not intended that

the requirement to “land as soon as practicable” be

construed to mean “as soon as possible.” Pilots retain the

prerogative of exercising their best judgment and are not

required to land at an unauthorized airport, at an airport

unsuitable for the type of aircraft flown, or to land only

minutes short of their intended destination.

3. IFR conditions. If the failure occurs in IFR

conditions, or if subparagraph 2 above cannot be

complied with, each pilot must continue the flight

according to the following:

(a) Route.

(1) By the route assigned in the last ATC

clearance received;

(2) If being radar vectored, by the direct

route from the point of radio failure to the fix, route,

or airway specified in the vector clearance;

(3) In the absence of an assigned route, by

the route that ATC has advised may be expected in a

further clearance; or

(4) In the absence of an assigned route or a

route that ATC has advised may be expected in a

further clearance by the route filed in the flight plan.

(b) Altitude. At the HIGHEST of the

following altitudes or flight levels FOR THE ROUTE

SEGMENT BEING FLOWN:

(1) The altitude or flight level assigned in

the last ATC clearance received;

(2) The minimum altitude (converted, if

appropriate, to minimum flight level as prescribed in

14 CFR Section 91.121(c)) for IFR operations; or

(3) The altitude or flight level ATC has

advised may be expected in a further clearance.

NOTE−

The intent of the rule is that a pilot who has experienced

two-way radio failure should select the appropriate

altitude for the particular route segment being flown and

make the necessary altitude adjustments for subsequent

route segments. If the pilot received an “expect further

clearance” containing a higher altitude to expect at a

specified time or fix, maintain the highest of the following

altitudes until that time/fix:

(1) the last assigned altitude; or 

(2) the minimum altitude/flight level for IFR

operations.

Upon reaching the time/fix specified, the pilot should

commence climbing to the altitude advised to expect. If the