AIM

8/15/19

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Preflight

b.

The FAA has identified three possible situations

where the failure to plan for an alternate airport when
flying IFR to such a destination airport could result in
a critical situation if the weather is less than forecast
and sufficient fuel is not available to proceed to a
suitable airport.

1.

An IFR flight to an airport where the

Minimum Descent Altitudes (MDAs) or landing
visibility minimums for 

all instrument approaches

are higher than the forecast weather minimums
specified in 14 CFR Section 91.167(b). For example,
there are 3 high altitude airports in the U.S. with
approved instrument approach procedures where all
of the MDAs are greater than 2,000 feet and/or the
landing visibility minimums are greater than 3 miles
(Bishop, California; South Lake Tahoe, California;
and Aspen

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Pitkin Co./Sardy Field, Colorado). In the

case of these airports, it is possible for a pilot to elect,
on the basis of forecasts, not to carry sufficient fuel to
get to an alternate when the ceiling and/or visibility
is actually lower than that necessary to complete the
approach.

2.

A small number of other airports in

mountainous terrain have MDAs which are slightly
(100 to 300 feet) below 2,000 feet AGL. In situations
where there is an option as to whether to plan for an
alternate, pilots should bear in mind that just a slight
worsening of the weather conditions from those
forecast could place the airport below the published
IFR landing minimums.

3.

An IFR flight to an airport which requires

special equipment; i.e., DME, glide slope, etc., in
order to make the available approaches to the lowest
minimums. Pilots should be aware that all other
minimums on the approach charts may require
weather conditions better than those specified in
14 CFR Section 91.167(b). An inflight equipment
malfunction could result in the inability to comply
with the published approach procedures or, again, in
the position of having the airport below the published
IFR landing minimums for all remaining instrument
approach alternatives.

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11. Flights Outside U.S. Territorial

Airspace

a.

When conducting flights, particularly extended

flights, outside the U.S. and its territories, full
account should be taken of the amount and quality of
air navigation services available in the airspace to be

traversed. Every effort should be made to secure
information on the location and range of navigational
aids, availability of communications and meteoro-
logical services, the provision of air traffic services,
including alerting service, and the existence of search
and rescue services.

b.

Pilots should remember that there is a need to

continuously guard the VHF emergency frequency
121.5 MHz when on long over-water flights, except
when communications on other VHF channels,
equipment limitations, or cockpit duties prevent
simultaneous guarding of two channels. Guarding of
121.5 MHz is particularly critical when operating in
proximity to Flight Information Region (FIR)
boundaries, for example, operations on Route R220
between Anchorage and Tokyo, since it serves to
facilitate communications with regard to aircraft
which may experience in-flight emergencies, com-
munications, or navigational difficulties.

REFERENCE

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ICAO Annex 10, Vol II, Paras 5.2.2.1.1.1 and 5.2.2.1.1.2.

c.

The filing of a flight plan, always good practice,

takes on added significance for extended flights
outside U.S. airspace and is, in fact, usually required
by the laws of the countries being visited or
overflown. It is also particularly important in the case
of such flights that pilots leave a complete itinerary
and schedule of the flight with someone directly
concerned and keep that person advised of the flight’s
progress. If serious doubt arises as to the safety of the
flight, that person should first contact the appropriate
FSS. Round Robin Flight Plans to Mexico are not
accepted.

d.

All pilots should review the foreign airspace

and entry restrictions published in the appropriate
Aeronautical Information Publication (AIP) during
the flight planning process. Foreign airspace
penetration without official authorization can involve
both danger to the aircraft and the imposition of
severe penalties and inconvenience to both passen-
gers and crew. A flight plan on file with ATC
authorities does not necessarily constitute the prior
permission required by certain other authorities. The
possibility of fatal consequences cannot be ignored in
some areas of the world.

e.

Current NOTAMs for foreign locations must

also be reviewed. The Notices to Airmen Publication
(NTAP), published every 28 days, contains consider-
able information pertinent to foreign flight. For
additional flight information at foreign locations,