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certificate. At uncontrolled airports, UAS operations are advised to operate well clear of all known manned 

aircraft operations. Pilots of manned aircraft are advised to follow normal operating procedures and are urged 

to monitor the CTAF for any potential UAS activity. At controlled airports, local ATC procedures may be in place 

to handle UAS operations and should not require any special procedures from manned aircraft entering or 

departing the traffic pattern or operating in the vicinity of the airport. 

d. 

In addition to approved UAS operations described above, a recently approved agreement between the FAA 

and the Department of Defense authorizes small UAS operations wholly contained within Class G airspace, and 

in no instance, greater than 1200 feet AGL over military owned or leased property. These operations do not 

require any special authorization as long as the UA remains within the lateral boundaries of the military 

installation as well as other provisions including the issuance of a NOTAM. Unlike special use airspace, these 

areas may not be depicted on an aeronautical chart. 

e. 

There are several factors a pilot should consider regarding UAS activity in an effort to reduce potential flight 

hazards. Pilots are urged to exercise increased vigilance when operating in the vicinity of restricted or other 

special use airspace, military operations areas, and any military installation. Areas with a preponderance of UAS 

activity are typically noted on sectional charts advising pilots of this activity. Since the size of a UA can be very 

small, they may be difficult to see and track. If a UA is encountered during flight, as with manned aircraft, never 

assume that the pilot or crew of the UAS can see you, maintain increased vigilance with the UA and always be 

prepared for evasive action if necessary. Always check NOTAMs for potential UAS activity along the intended 

route of flight and exercise increased vigilance in areas specified in the NOTAM. 

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7.  Mountain Flying 

a. 

Your first experience of flying over mountainous terrain (particularly if most of your flight time has been 

over the flatlands of the Midwest) could be a 

never-to-be-forgotten nightmare

 if proper planning is not done and 

if you are not aware of the potential hazards awaiting. Those familiar section lines are not present in the 

mountains; those flat, level fields for forced landings are practically nonexistent; abrupt changes in wind 

direction and velocity occur; severe updrafts and downdrafts are common, particularly near or above abrupt 

changes of terrain such as cliffs or rugged areas; even the clouds look different and can build up with startling 

rapidity. Mountain flying need not be hazardous if you follow the recommendations below. 

b.  File a Flight Plan. 

Plan your route to avoid topography which would prevent a safe forced landing. The 

route should be over populated areas and well known mountain passes. Sufficient altitude should be maintained 

to permit gliding to a safe landing in the event of engine failure. 

c. 

Don’t fly a light aircraft when the winds aloft, at your proposed altitude, exceed 35 miles per hour. Expect 

the winds to be of much greater velocity over mountain passes than reported a few miles from them. Approach 

mountain passes with as much altitude as possible. Downdrafts of from 1,500 to 2,000 feet per minute are not 

uncommon on the leeward side. 

d. 

Don’t fly near or above abrupt changes in terrain. Severe turbulence can be expected, especially in high 

wind conditions. 

e.  Understand Mountain Obscuration.

 The term Mountain Obscuration (MTOS) is used to describe a 

visibility condition that is distinguished from IFR because ceilings, by definition, are described as “above ground 

level” (AGL). In mountainous terrain clouds can form at altitudes significantly higher than the weather reporting 

station and at the same time nearby mountaintops may be obscured by low visibility. In these areas the ground 

level can also vary greatly over a small area. Beware if operating VFR

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top. You could be operating closer 

to the terrain than you think because the tops of mountains are hidden in a cloud deck below. MTOS areas are 

identified daily on The Aviation Weather Center located at: http://www.aviationweather.gov. 

f. 

Navigating in confined terrain when flying through mountain passes can be challenging. For high

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traffic 

mountain passes, VFR checkpoints may be provided on VFR navigation charts to increase situational awareness 

by indicating key landmarks inside confined terrain. A collocated VFR waypoint and checkpoint may be 

provided to assist with identifying natural entry points for commonly flown mountain passes. Pilots should 

Potential Flight Hazards 

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