Cabin Altitude

[jonss1948 20]

This is a small annoyance that I'm certain is fixable and a fault of my own and not the 747-400 programming. I have done most of my takeoff's and landings at near sea-level so this has not been a problem before but I'm attempting a journey from La Paz (sllp 13,200ft) to Rio (sbgl). I also start with a c&d cockpit (previously established at sea-level and imported). Bottom line: After a few minutes I get a 'Cabin Altitude' warning and alarm. I can shut the alarm off ok but the red 'Cabin Altitude' sign remains and is not cancellable via the eicas. I've porked about with the settings on the overhead but cannot get rid of it. I even read the instruction manual.I suppose this poses a couple of questions:1) How do I correct this?2) Will this affect my 'V' speeds? I'm certainly using all the runway to achieve V2.JonAdded: I start the flight by using the default Cessna 172, shutting everything down, except avionics, then reselecting my 747-400 once inide the program.

[markadeane 272]

Take a look at the 'limitations' section of the manual - specifically the maximum pressure altitude for t/o and landing. ;-)

[NJ_Flyer 3]

Considering the Pressure warning sounds at 10,000ft ASL. Your at and airport at 13000ASL, so it wont take long for the cabin altitude to reach 13000. Which is not a good thing for repeat service.

[jonss1948 20]

Thank you for your help. See, here's me assuming that an airport designated 'international' would accept 747's. Just like me to choose one of the highest airports in the world to take off from. I've actually been searching the net to find a page I accessed a year or so ago which listed the largest aircraft acceptable by each airport. I have not found it yet. My next challenge will be an ILS approach into SION in my 737. That'll be fun.Jon

[neilbradley1 2]

Jon,Been there, an interesting approach with the ILS off-set, just make sure your approach is stabilised and I suggest you use Vref+10, to give you more control while hand flying the last segment. Set the auto brakes to max and you will stop in plnet of time.NeilYPAD

[mozart 1]

>Thank you for your help. See, here's me assuming that an>airport designated 'international' would accept 747's. Just>like me to choose one of the highest airports in the world to>take off from. I've actually been searching the net to find a>page I accessed a year or so ago which listed the largest>aircraft acceptable by each airport. I have not found it yet.Jon,How funny you should post this right now. Look in the forum as I have also told the story of some issues I had flying to SLLP (in my case I was going there, not leaving there on my 744) just a few days ago. Cabin altitude, same problem here. But I had another issue: no runways listed on the DEP/ARR page of the FMC. So you imagine me, coming in from SEQU on my Iberia 747-400, cleared to runway 28 - i.e., on the mountainous side of the airport requiring some steep turns just before touchdown - for which I couldn't find an approach map, runway not listed in the FMC so no way to construct my own approach procedure, visibility wasn't great, very challenging terrain on that side of the field - and basically I was hand flying, when suddenly I had the cabin altitude alert and that stupid horn going off!!!! Try hand flying an approach with a short lineup, in difficult terrain, poor visibility, a place you don't know, and then having to open the overhead and basically guessing what button to press to solve a problem you've never encountered before and you've not been prepared to encounter.I was pumping adrenalin.Concerning the 747 at La Paz in "real life": Lufthansa used to go to La Paz on the 747 in the 80s and maybe also in the 90s, but that was the 747-200.So my flight out of La Paz was on the RFP 747-200 in Aero Sur colours to Cuzco. The plane wasn't heavy, 235 tons TOW, Vr at 119kn, V2 at 138kn - but still the runway was feeling short.I love flying around Bolivia!>My next challenge will be an ILS approach into SION in my 737.>That'll be fun.>>JonThat's peanuts compared to some of the challenges in the Andes airports (I've done Sion with an Airbus). Try properly flying the circling approach to runway 35 at Quito, and when you master that, try runways 31R and 31L at Bogota - of course all with the 747-400. If you look for more mountain and altitude challenges, PM me, I have a whole list of them and also the scenery files that go with them.CheersChris

[jonss1948 20]

That's peanuts compared to some of the challenges in the Andes airports (I've done Sion with an Airbus). Try properly flying the circling approach to runway 35 at Quito, and when you master that, try runways 31R and 31L at Bogota - of course all with the 747-400. If you look for more mountain and altitude challenges, PM me, I have a whole list of them and also the scenery files that go with them.

I must obtain a higher proficiency before attempting these things. I realise I can 'dust off' the aircraft after buying the real estate but I have not, as yet, attempted any of the failure scenarios or, for that matter, any 'circle to land' approaches. Not because I'm fwightened, more wishing to understand the complexities, theories and practicalities of these birds. Another aspect is observing the realities of such airports and only wishing to attempt landings at ie: SION in an aircraft capable of such a practice. I recall 757's being the largest aircraft accepted. I agree that flying around Bolivia is very interesting and even with the default terrain, quite breathtaking. I wish to become more adept at pilotage so that Bolivia does'nt become Oblivia, in my case. I will take up your kind offer and PM you for your list of difficult and dangerous approaches. Thanks to everyone for your valuable responses.Jon