B747 crew got the cabin high altitude warning horn.

Attributes
ACN	478430
Time
Date	200006
Day	Thu
Local Time Of Day	1801 To 2400
Place
State Reference	FO
Altitude	msl single value : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : rjtg.artcc
Operator	common carrier : air carrier
Make Model Name	B747-100
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : vacating altitude climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 100 flight time total : 9000 flight time type : 2000
ASRS Report	478430
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : published procedure non adherence : company policies other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : cabin altitude warning
Resolutory Action	other
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

At approximately FL240, an intermittent warning horn began to sound. We checked all takeoff warning items, found all ok, then realized the cabin was not pressurized, cabin altitude just over 10000 ft. Found that so had forgotten to turn on air conditioning packs. Pilots went on oxygen, turned on packs, and leveled at FL250 until cabin began to pressurize. When cabin stable, we returned to normal operation and continued climb. So is very new to aircraft, and just forgot the packs. Captain could have seen the problem developing from his seat, but was flying, so could not be expected to watch the panel. After it started, the situation was handled well.

Original NASA ASRS Text

Title: B747 CREW GOT THE CABIN HIGH ALT WARNING HORN.

Narrative: AT APPROX FL240, AN INTERMITTENT WARNING HORN BEGAN TO SOUND. WE CHKED ALL TKOF WARNING ITEMS, FOUND ALL OK, THEN REALIZED THE CABIN WAS NOT PRESSURIZED, CABIN ALT JUST OVER 10000 FT. FOUND THAT SO HAD FORGOTTEN TO TURN ON AIR CONDITIONING PACKS. PLTS WENT ON OXYGEN, TURNED ON PACKS, AND LEVELED AT FL250 UNTIL CABIN BEGAN TO PRESSURIZE. WHEN CABIN STABLE, WE RETURNED TO NORMAL OP AND CONTINUED CLB. SO IS VERY NEW TO ACFT, AND JUST FORGOT THE PACKS. CAPT COULD HAVE SEEN THE PROB DEVELOPING FROM HIS SEAT, BUT WAS FLYING, SO COULD NOT BE EXPECTED TO WATCH THE PANEL. AFTER IT STARTED, THE SIT WAS HANDLED WELL.

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.