Alarm in high altitude take off

[capizolano]

Hi, i has try 4 times to take off in SLCB airport at 8400 ft altitude. with diferrents settings on FMC take off, but always, in climb start sound alarm and in recall iluminate "overhead", i think something is wrong in settings for take off, but i don´t know wath is. maybe is the pressurization, maybe the engines. Anyone know what to do? thank you

[WR269]

Hi, i has try 4 times to take off in SLCB airport at 8400 ft altitude. with diferrents settings on FMC take off, but always, in climb start sound alarm and in recall iluminate "overhead", i think something is wrong in settings for take off, but i don´t know wath is. maybe is the pressurization, maybe the engines. Anyone know what to do? thank you

That would be the Cabin Altitude warning. It is probably set for an altitude lower than your present altitude. Once you start your flight, if pressurisation is on Auto, it will lower the cabin altitude to the setting you need, or you can set it Manual and do it yourself

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[capizolano]

9 hours ago, WR269 said:

That would be the Cabin Altitude warning. It is probably set for an altitude lower than your present altitude. Once you start your flight, if pressurisation is on Auto, it will lower the cabin altitude to the setting you need, or you can set it Manual and do it yourself

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i has made it, but the same, alarm and "overhead" in recall

[mmerelles]

@capizolano please attach a screen shot of your entire overhead panel configuration when you are ready for takeoff. that would be easy to see what is going on.

Also be sure you have set to FLT mode, on ground mode (default) it will not pressurize.

Edited June 22, 2016 by mmerelles

[capizolano]

i found  notes for 737-300 and says that max landing and take off altitutde is 8.400 ft. maybe the problem is that. Not is possible make take off in this airport

[mmerelles]

i did the departure for you, haven't had any alarm.

departing runway 32 atovo

destination saez fl350

50 tons of zfw and 9 tons of fuel

 

ohhh men the departure was a bit scary via runway 32 those montains ahead are so high, even doing the 180 turnback for the trasition... that was close call! The aircraft loaded heavy 50 tons at that altitude requires the entire runway and a slow climb out. 

 

the only particular config i did was to left the apu on to keep pressurization going from the apu to get the most out of those engines for takeoff/initial climbout

 

[capizolano]

8 minutes ago, mmerelles said:

i did the departure for you, haven't had any alarm.

departing runway 32 atovo

destination saez fl350

50 tons of zfw and 9 tons of fuel

 

ohhh men the departure was a bit scary via runway 32 those montains ahead are so high, even doing the 180 turnback for the trasition... that was close call! The aircraft loaded heavy 50 tons at that altitude requires the entire runway and a slow climb out. 

 

the only particular config i did was to left the apu on to keep pressurization going from the apu to get the most out of those engines for takeoff/initial climbout

 

thank you, i will try it

[mmerelles]

1 minute ago, capizolano said:

thank you, i will try it

please do a screen capture of your overhead panel when aligned on the runway prior to takeoff. In such case you get the alarm back you share the image to see your config.

[capizolano]

Solved captain, thank you. take off and climb with APU ON to FL340, at FL340 GEn1 & 2 ON, APU Off, and ready. No alarm

[mmerelles]

2 minutes ago, capizolano said:

Solved captain, thank you. take off and climb with APU ON to FL340, at FL340 GEn1 & 2 ON, APU Off, and ready. No alarm

a few observations

1. once the engines are running prior to taxi you must enable GEN1 & GEN2 and transfer the electricity to load to the engine generators (you never takeoff using the apu generators you have no redundancy at all)

2. to use the apu to keep pressurization going, leave the apu on but on the BLEED panel only enable apu bleed to feed the packs, leave eng1/2 bleed to off.

3. i think the apu has a maximum recommended limit as well so do not leave the apu on forever, once you completed the takeoff procedure you can feed the packs via the engines.

 

here you have a good video to achieve this, while LOWI is not a high altitude airport, he configures the aircraft to get high performance due to mountains surrounding.

 

[capizolano]

thank you for your observations. i has searched the procedures for tis type of take off but i don´t has found anything. thakn you a lot.