Hi,

 

I would like to buy and fly to some of the LatinVFR airports in Bolivia and Peru like El Alto at 13,000 feet PA. My Topcat wont give me any info because it says pressure altitude over 10000 feet. I know some airlines get some mods for their 73's to operate here so I am wondering how I can get performance data for this high. Also will the FMS spew out an error. How do I get the cabin alt horn to not go off. From what I understand PMDG did not model the high altitude variants but I am wondering if their is a work around.

 

Thanks

The airline has to buy a supplemental certificate of sorts - that would include things like modifications to pressurization system, manuals with high altitude procedures, as well as performance manuals ammendment and/or Boeing Performance program data for pressure altitude 10 000+ feet.

Yea but how do you do it realistically in the NGX? Problem is I do not think it is modeled which is fine. But the issues are:

 

No way to kill the above 10,000 foot cabin warning. Or is there?

Performance charts do not go up that high. Are there any?

Does the landing altitude go up that high? Above 10,000 feet or 8,400?

 

I am too much of a stickler for realism but I would like to do it as closely to the real world counterparts as possible.

http://www.boeing.co...se_000918a.html

 

http://www.chinadail...ent_7131374.htm

 

Best regards,

Robin.

Yea but how do you do it realistically in the NGX? Problem is I do not think it is modeled which is fine. But the issues are:

 

No way to kill the above 10,000 foot cabin warning. Or is there?

Performance charts do not go up that high. Are there any?

Does the landing altitude go up that high? Above 10,000 feet or 8,400?

 

I am too much of a stickler for realism but I would like to do it as closely to the real world counterparts as possible.

 

Hi Marc,

 

ALT HORN CUTOUT switch silences cabin altitude warning horn (horn sounds when cabin altitude reaches 10,000'). Basic AFM performance data is only valid up to the stated Maximum Takeoff / Landing pressure altitude (typically 8,400 ft msl). Performance data above Basic AFM limits are found in AFM High Altitude Appendix “Operation at Airport Pressure Altitudes up to ________ feet.

 

The LAND ALTITUDE INDICATOR range is from -1000 to 14,000 in 50 ft increments.

 

High Altitude Operations is any time the airport pressure altitude exceeds Basic AFM Section 1.0 Limitation on Maximum Takeoff / Landing pressure altitude (typically 8,400 ft msl). There re lots of tecnical issues associated with high altitude operations,..particularly:

 

High TAS at high altitude results in high ground speeds

Tire speed ratings become critical

Brake Energy can become critical on takeoffs

Brake Cooling can become critical on landings

Fuse Plug melt becomes possible after normal landings

Cabin Altitude Warning Horn logic may need modification (horn sounds at 10,000 ft cabin alt. normally)

High enroute terrain is common, dictates EO driftdown,

Emergency Descent, passenger O2 analysis

Passenger Chemical Oxygen Generators may be inadequate (12 minutes generators standard)

ETP and PNR becomes a factor in flight planning

Auto Mask Drop logic may need modification (masks drops at 14,000 ft cabin alt. normally)

APU start capability has to be verified before engine shutdown

Crew procedures for Pressurization Control may be different

FMC V-speeds may be invalid at extreme high altitude airports (e.g. NG FMC V-speeds valid from -2,000 ft to 13,500 ft msl)

Only certain Flaps can be used for takeoffs / landings (NG: F1 / F15)

Engine thrust lapse with increasing altitude results in reduced permissible TOW’s

High TAS results in high turn radius in possibly tight terrain, esp. important for EO turnback maneuvers

ISA + 30 deg C is not uncommon for high altitude airports in the Summer

Landing above 10,000 ft, Cockpit crew should put on their O2 masks at top-of-descent (TOD)

Climbing out at the FAR Min. Climb gradient (2.4% for twins) at high elevation airports results in astonishingly high ground speeds.

 

You Must look beyond documentation variations and check multiple data sources (OM, FCTM, FPPM, DDG, STAS, etc) and then apply real “operational” sense into your procedures.

 

High Altitude Oxygen System Componentson the NG are:

 

scf graphic composite cylinders (1,600 psi) located in aft cargo compartment with (9) individual pressure regulators.

 

Remote fill system along the right hand aft side wall of the aft cargo compartment (up to 12 cylinders possible).

 

Low pressure main distribution loop and distribution system plumbing.

 

Wiring for O2 indication and deployment system.

 

Flt deck O2 control module on overhead P5 panel.

 

Hope this helps,..

 

 

Regards

The above covers pretty much everything! A couple of points to raise re: oxygen. Firstly it is mandatory for every flightdeck crew to don his/her mask above a cabin altitude of 10,000ft for whatever reason. As far as modelling "that" in the sim I haven't come across any that cater for the entire range of possibilities. The free VC10 update is the only one as far as I know.

Secondly oxygen delivery systems are rated for at least four hours of supply. This is based on the first 15 mins at high emergency pressure and thereafter at demand pressure. This allows for the a/c to fly to an alternate maintaining 10-15,000ft.

vololiberista

This is a typical profile Which is also modelled in the above:-

 

 

Without the specific customer options for an NG specced up for high altitude airport operations, you are gonna have blag things a bit. As others have noted, the main things that are different are oxygen supplies on board, tweaks to the cabin alt warning horn and cabin pressurisation system, and possibly engine tweaks via the FMC.

 

Most of the other things which get tweaked are unfortunately not really relevant as far as FSX is concerned; i.e. you can land at 500 mph in FSX and you won't burst a tire, but what you might do with the PMDG NG is overheat the brakes owing to higher landing speeds. You might potentially be able to use TSR Autobrake though, in tweaking runway handling to compensate for stuff. Another problem is of course FMC differences, and that's likely to be another area where you will just have to blag it.

 

Of interest to you might be this from Chris Brady's site, written by a VARIG pilot on the 737:

 

http://www.b737.org....apazairport.htm

 

Al

The above covers pretty much everything! A couple of points to raise re: oxygen. Firstly it is mandatory for every flightdeck crew to don his/her mask above a cabin altitude of 10,000ft for whatever reason. As far as modelling "that" in the sim I haven't come across any that cater for the entire range of possibilities. The free VC10 update is the only one as far as I know.

Secondly oxygen delivery systems are rated for at least four hours of supply. This is based on the first 15 mins at high emergency pressure and thereafter at demand pressure. This allows for the a/c to fly to an alternate maintaining 10-15,000ft.

vololiberista

This is a typical profile Which is also modelled in the above:-

 

 

 

I think you misunderstand,..

 

You're correct about the Masks,..That's what i was trying to say when i said "Landing above 10,000 ft, Cockpit crew should put on their O2 masks at top-of-descent (TOD)"

 

Classics & NG's: Passenger Oxygen will deploy automatically above 14,000ft cabin alt or when switched on from the aft overhead panel. No oxygen will flow in a PSU until a mask in that PSU has been pulled.

 

There is 12 minutes supply of oxygen in each PSU, this is based upon:

 

0.3 min delay at 37,000ft

3.1 min descent to 14,000ft

7.6 min hold at 14,000ft

1.0 min descent to 10,000ft

 

Regards

It's not a case of misunderstanding!! The oxygen system I described is designed for long distance flights. It too deploys automatically above 14,000ft but after the emergency pressure being presented for 15 minutes it reverts to a normal on demand therapeutic supply which if carefully managed can last the rest of the flight.

For those who aren't familiar with 737 systems this is a good site. http://www.b737.org.uk/index.htm

vololiberista

It's not a case of misunderstanding!! The oxygen system I described is designed for long distance flights. It too deploys automatically above 14,000ft but after the emergency pressure being presented for 15 minutes it reverts to a normal on demand therapeutic supply which if carefully managed can last the rest of the flight.

For those who aren't familiar with 737 systems this is a good site. http://www.b737.org.uk/index.htm

vololiberista

 

Excuse me,..DO NOT yell at me first of all (your exclamations imply that) Yes, i believe it is a case of misunderstanding,..the system i described before "Passenger Chemical Oxygen Generators may be inadequate (12 minutes generators standard)" Is the STANDARD system, hence why i listed is as INADEQUATE,..i wasn't talking about the system you describe, I placed it under the heading of Technical issues for that reason as well.

 

Thanks for the link by the way. At the same website you can see the oxygen system which i said would be inadequate and what i'm talking about at this link: http://www.b737.org....assenger_Oxygen

 

 

I am / was trying to help you based on my experience because i've flown aircraft with the High Altitude Landing System in my career.

The high altitude option is something we may (note that I said "may" not "will") include with SP2. It's on the list to be considered...

Thanks. My main concern is takeoff and landing performance. I flew into and out of SJSU the capiol of Bolivia. Latin VFR makes this and it is fantastic, crazy slopped runway and all. The guy even models pavement irregularities and with the touchdown sound mod is jus great. Anyway Topcat goes up to 10,000 and thats it. So using topcat yesterday I was able to maximize payload for a trip to Santiago with max payload for conditions. I used bump thrust for good measure on the actual takeoff. I found tha PMDG very acurately modeled everything. I was astounded, I had 90 foot margin and that was about where I was 35 feet over the runway, 90 feet or so before it. That was just the coolest thing in the world. Now I am at Quito which is at 9,250 feet. The landing was a real smoker even with flaps 40. So I make as much moola as possible I pushed the payload for max landing weight for the altitude for the trip from Santiago which was 138.6 lbs leaving 6.0 fuel left. I landed with 5.7, just enough for that location in the 900. I would like to use a few other large airports like Cuzco at 13,000 something. I thing I can extrapolate the NG charts for above 10,000. Even though this would not be done in the real world I think it will allow me to maximize payload for Cuzco and give me an idea of fuel range to max destination. I just try to keep it real minus actually wearing my oxygen mask in front of the computer. That may scare the squirrels.

I found tha PMDG very acurately modeled everything. I was astounded, I had 90 foot margin and that was about where I was 35 feet over the runway, 90 feet or so before it. That was just the coolest thing in the world.

 

 

Well then unless you had a V1 cut, something was wrong actually... you should have way more...