AIM Text
- 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.
Source: FAA Aeronautical Information Manual · current edition · paragraph 7-6-5.
Research Notes
AIM 7-6-5 covers Recognizing Icing Conditions — visual and instrument cues that ice is forming.
Visual cues:
- Ice accumulating on wing leading edge (look at deicer boots or wing strut tape)
- Ice on windshield, propeller spinner
- Ice on OAT probe
- Ice on antennas and pitot tube
Performance cues:
- Loss of climb performance
- Increased fuel burn for same airspeed
- Airspeed decay at constant power
- Higher angle of attack required to maintain altitude
The 'I'm flying through cloud at -5°C' rule: If you're in visible moisture (cloud, drizzle, freezing rain) at temperatures from +2°C to -20°C, expect ice. The peak icing range is -2°C to -10°C with maximum droplet size.