DHC8 flight crew take off with both aircraft packs in the off position.

Attributes
ACN	692742
Time
Date	200603
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : btg.vortac
State Reference	WA
Altitude	msl single value : 15000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zse.artcc
Operator	common carrier : air carrier
Make Model Name	Dash 8-400
Operating Under FAR Part	Part 121
Flight Phase	climbout : initial
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 1500
ASRS Report	692742
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure non adherence : company policies
Independent Detector	aircraft equipment other aircraft equipment : cabin alt warning light
Resolutory Action	flight crew : overcame equipment problem
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Both aircraft packs were inadvertently left in 'off' position. Normal position is 'automatic' or 'manual.' bleeds switches were on. At 15000 ft MSL (cruise altitude) cabin altitude warning light came on. Cabin altitude showed 9300 ft and 2.5 psid. Aircraft pack switches immediately selected on (manual position). Aircraft re-pressurized normally. Comments: the position of pack and bleed switches is normally checked on the captain's originating flow (not a checklist item). Bleed switch position is a checklist; but pack switch position; on the 'after start; 'before takeoff;' and 'after takeoff' checklists. It is always assumed to check the pack switch position along with bleed switch position. Normally; the pack switches are always on in either automatic or manual position and never selected off except for abnormal operation. Only bleeds select on/off for takeoff/landing performance requirements. However; a new common practice is to cycle the pack switches off for approximately 10 seconds; then back on; to clear faults in the digital pack controls that sometimes cause temperature control problems. This may be why the pack switches were left in 'off' position. It is also interesting to note that we were maintaining approximately 2.5 psi at 15000 ft MSL with bleeds on; but aircraft packs off.

Original NASA ASRS Text

Title: DHC8 FLT CREW TAKE OFF WITH BOTH ACFT PACKS IN THE OFF POS.

Narrative: BOTH ACFT PACKS WERE INADVERTENTLY LEFT IN 'OFF' POS. NORMAL POS IS 'AUTO' OR 'MANUAL.' BLEEDS SWITCHES WERE ON. AT 15000 FT MSL (CRUISE ALT) CABIN ALT WARNING LIGHT CAME ON. CABIN ALT SHOWED 9300 FT AND 2.5 PSID. ACFT PACK SWITCHES IMMEDIATELY SELECTED ON (MANUAL POS). ACFT RE-PRESSURIZED NORMALLY. COMMENTS: THE POS OF PACK AND BLEED SWITCHES IS NORMALLY CHKED ON THE CAPT'S ORIGINATING FLOW (NOT A CHKLIST ITEM). BLEED SWITCH POS IS A CHKLIST; BUT PACK SWITCH POS; ON THE 'AFTER START; 'BEFORE TKOF;' AND 'AFTER TKOF' CHKLISTS. IT IS ALWAYS ASSUMED TO CHK THE PACK SWITCH POS ALONG WITH BLEED SWITCH POS. NORMALLY; THE PACK SWITCHES ARE ALWAYS ON IN EITHER AUTO OR MANUAL POS AND NEVER SELECTED OFF EXCEPT FOR ABNORMAL OP. ONLY BLEEDS SELECT ON/OFF FOR TKOF/LNDG PERFORMANCE REQUIREMENTS. HOWEVER; A NEW COMMON PRACTICE IS TO CYCLE THE PACK SWITCHES OFF FOR APPROX 10 SECONDS; THEN BACK ON; TO CLR FAULTS IN THE DIGITAL PACK CTLS THAT SOMETIMES CAUSE TEMP CTL PROBS. THIS MAY BE WHY THE PACK SWITCHES WERE LEFT IN 'OFF' POS. IT IS ALSO INTERESTING TO NOTE THAT WE WERE MAINTAINING APPROX 2.5 PSI AT 15000 FT MSL WITH BLEEDS ON; BUT ACFT PACKS OFF.

Data retrieved from NASA's ASRS site as of January 2009 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.