Issue Number 220
October 1997
A Monthly Safety Bulletin from The Office of the NASA Aviation Safety Reporting System
P.O. Box 189, Moffett Field, CA 94035-0189

"Did You Say What I Heard?"

Mandatory readback of certain parts of clearances provides a mechanism to reduce misunderstandings between ATC and flight crews. An ATC supervisor reports on a readback error that slipped by both him and an ATC trainee, with a potentially hazardous result.

Another controller reports that even when the readback of the clearance is correct, sometimes it's the wrong aircraft doing the reading back. We all get hurried on occasion. Kudos to the pilots out there for whom safety, not time, is the number one priority.

Careful readbacks - and additional clarification, if necessary - are especially important for both pilots and controllers when aircraft with similar-sounding callsigns are on the frequency.

Airspace "Busts"

Turbulence and an unauthorized penetration of airspace may not seem obviously related. In two separate reports, however, turbulence, or rather, a pilot's attempt to avoid it, led to an airspace "bust." A corporate Captain explains: Next, a general aviation (GA) pilot in a restored military trainer was also seeking a smoother ride when turbulence took away his chart and added a new wrinkle to the flight. If pilots want to remain VFR while flying in MVFR conditions, they should be sure to maintain adequate back-up navigation to verify they are clear of controlled airspace.

When Things Seen Are Not As They Seem

The old adage that "seeing is believing" is not always true, as a GA pilot learned in this report of a fuel mix-up. Next, the Captain of an air taxi cargo flight discovered that diamonds aren't every pilot's best friend.

Lights! Action! Oops!

In another report, an air carrier crew fell victim to an admittedly "well-known optical illusion." Any apparent aircraft movement should be suspect. This crew was fortunate to recognize the problem before a ground collision occurred.

"A Certain Slant of Light"

- Emily Dickinson At night, lights on and in the vicinity of the airport can also result in optical illusions, as illustrated in a report by a crew member of a cargo jet: Faced with an unknown and possibly very hazardous ground conflict, the crew's decision to reject the takeoff was the safest course of action.

A general aviation pilot experienced a surprising illusion on what was an otherwise beautiful night for flying.

The strobe lights on most helicopters are mounted at each end of the horizontal stabilizer, hence are usually only about 5-6 feet apart.

ASRS Recently Issued Alerts On...
An aileron cable failure on a B737-200
FMS map shifts resulting in an IFR missed approach
Timeliness of Land-and-Hold-Short instructions by ATC
A New Jersey SID generating 25 air carrier pilot complaints
Severe control problems due to a wing crack on an EMB-120
August 1997 Report Intake
 Air Carrier Pilots
 General Aviation Pilots