Aeronautical Information Manual (AIM)

AIM

4/3/14

7−5−2

Potential Flight Hazards

at least 2,000 feet. Additionally, new towers may not

be on your current chart because the information was

not received prior to the printing of the chart.

c. Overhead Wires.

Overhead transmission and

utility lines often span approaches to runways,

natural flyways such as lakes, rivers, gorges, and

canyons, and cross other landmarks pilots frequently

follow such as highways, railroad tracks, etc. As with

antenna towers, these high voltage/power lines or the

supporting structures of these lines may not always be

readily visible and the wires may be virtually

impossible to see under certain conditions. In some

locations, the supporting structures of overhead

transmission lines are equipped with unique sequence

flashing white strobe light systems to indicate that

there are wires between the structures. However,

many power lines do not require notice to the FAA

and, therefore, are not marked and/or lighted. Many

of those that do require notice do not exceed 200 feet

AGL or meet the Obstruction Standard of 14 CFR

Part 77 and, therefore, are not marked and/or lighted.

All pilots are cautioned to remain extremely vigilant

for these power lines or their supporting structures

when following natural flyways or during the

approach and landing phase. This is particularly

important for seaplane and/or float equipped aircraft

when landing on, or departing from, unfamiliar lakes

or rivers.

d. Other Objects/Structures.

There are other

objects or structures that could adversely affect your

flight such as construction cranes near an airport,

newly constructed buildings, new towers, etc. Many

of these structures do not meet charting requirements

or may not yet be charted because of the charting

cycle. Some structures do not require obstruction

marking and/or lighting and some may not be marked

and lighted even though the FAA recommended it.

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4. Avoid Flight Beneath Unmanned

Balloons

The majority of unmanned free balloons

currently being operated have, extending below

them, either a suspension device to which the payload

or instrument package is attached, or a trailing wire

antenna, or both. In many instances these balloon

subsystems may be invisible to the pilot until the

aircraft is close to the balloon, thereby creating a

potentially dangerous situation. Therefore, good

judgment on the part of the pilot dictates that aircraft

should remain well clear of all unmanned free

balloons and flight below them should be avoided at

all times.

Pilots are urged to report any unmanned free

balloons sighted to the nearest FAA ground facility

with which communication is established. Such

information will assist FAA ATC facilities to identify

and flight follow unmanned free balloons operating

in the airspace.

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5. Unmanned Aircraft Systems

Unmanned Aircraft Systems (UAS), formerly

referred to as “Unmanned Aerial Vehicles” (UAVs)

or “drones,” are having an increasing operational

presence in the NAS. Once the exclusive domain of

the military, UAS are now being operated by various

entities. Although these aircraft are “unmanned,”

UAS are flown by a remotely located pilot and crew.

Physical and performance characteristics of un-

manned aircraft (UA) vary greatly and unlike model

aircraft that typically operate lower than 400 feet

AGL, UA may be found operating at virtually any

altitude and any speed. Sizes of UA can be as small

as several pounds to as large as a commercial

transport aircraft. UAS come in various categories

including airplane, rotorcraft, powered−lift (tilt−

rotor), and lighter−than−air. Propulsion systems of

UAS include a broad range of alternatives from

piston powered and turbojet engines to battery and

solar−powered electric motors.

To ensure segregation of UAS operations from

other aircraft, the military typically conducts UAS

operations within restricted or other special use

airspace. However, UAS operations are now being

approved in the NAS outside of special use airspace

through the use of FAA−issued Certificates of Waiver

or Authorization (COA) or through the issuance of a

special airworthiness certificate. COA and special

airworthiness approvals authorize UAS flight

operations to be contained within specific geographic

boundaries and altitudes, usually require coordina-

tion with an ATC facility, and typically require the

issuance of a NOTAM describing the operation to be

conducted. UAS approvals also require observers to

provide “see−and−avoid” capability to the UAS crew

and to provide the necessary compliance with 14 CFR

Section 91.113. For UAS operations approved at or

above FL180, UAS operate under the same

requirements as that of manned aircraft (i.e., flights