AIM 

3/21/24 

erected in a matter of hours, installed with guyed wires, and constructed from a galvanized material often making 

them difficult to see in certain atmospheric conditions. Markings for these towers include alternating bands of 

aviation orange and white paint, and high

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visibility sleeves installed on the outer guy wires. However, not all 

MET towers follow these guidelines, and pilots should be vigilant when flying at low altitude in remote or rural 

areas. 

f. 

Other Objects/Structures. There are other objects or structures that could adversely affect your flight such 

as temporary 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. VFR pilots should carefully review  NOTAMs for temporary or permanent 

obstructions along the planned route of flight during their preflight preparations. Particular emphasis should be 

given to obstructions in the vicinity of the approach and departure ends of the runway complex or any other areas 

where flight below 500 feet AGL is planned or likely to occur. 

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5.  Avoid Flight Beneath Unmanned Balloons 

a. 

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. 

b. 

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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6.  Unmanned Aircraft Systems 

a. 

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 unmanned 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

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lift (tilt

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rotor), and 

lighter

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than

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air. Propulsion systems of UAS include a broad range of alternatives from piston powered and 

turbojet engines to battery and solar

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powered electric motors. 

b. 

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

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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 coordination 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

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and

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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 are operated 

under instrument flight rules, are in communication with ATC, and are appropriately equipped). 

c. 

UAS operations may be approved at either controlled or uncontrolled airports and are typically 

disseminated by NOTAM. In all cases, approved UAS operations must comply with all applicable regulations 

and/or special provisions specified in the COA or in the operating limitations of the special airworthiness 

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Potential Flight Hazards