<< >> NASA ASRS Report 622344, September 2003

B737-900 PIC complains of the audio panel design wherein the GPWS, altitude alert and other signals are too loud in the crew's headsets, thereby possibly creating a loss of communication with ATC.

Attributes
ACN	622344
Time
Date	200309
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 5000
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-900
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : takeoff descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	622344
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : unable none taken : anomaly accepted
Consequence	other
Supplementary
Problem Areas	Company Environmental Factor Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Aural warnings in B737-900 aircraft (approaching/departing altitude, GPWS, voice altitude calls from 100 ft down during landing, etc) are loud enough in captain's headset so as to drown out radio calls. Aural warnings over the overhead speaker, as in the B-300/500/700/800, are sufficiently loud enough to make the crew aware of warnings. First officer does not receive warnings in headset in B-900 type aircraft. There seems to be no consistency in B-900 aircraft, some have headset warnings, some do not.

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Original NASA ASRS Text

Title: B737-900 PIC COMPLAINS OF THE AUDIO PANEL DESIGN WHEREIN THE GPWS, ALT ALERT AND OTHER SIGNALS ARE TOO LOUD IN THE CREW'S HEADSETS, THEREBY POSSIBLY CREATING A LOSS OF COM WITH ATC.

Narrative: AURAL WARNINGS IN B737-900 ACFT (APCHING/DEPARTING ALT, GPWS, VOICE ALT CALLS FROM 100 FT DOWN DURING LNDG, ETC) ARE LOUD ENOUGH IN CAPT'S HEADSET SO AS TO DROWN OUT RADIO CALLS. AURAL WARNINGS OVER THE OVERHEAD SPEAKER, AS IN THE B-300/500/700/800, ARE SUFFICIENTLY LOUD ENOUGH TO MAKE THE CREW AWARE OF WARNINGS. FO DOES NOT RECEIVE WARNINGS IN HEADSET IN B-900 TYPE ACFT. THERE SEEMS TO BE NO CONSISTENCY IN B-900 ACFT, SOME HAVE HEADSET WARNINGS, SOME DO NOT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.