737-800 service ceiling?
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737-800 service ceiling?
This is a photo of my Garmin 96C (left) and a 738's IFE screen showing the flight's progress (right) from Darwin to Melbourne. My question is, are we really cruising at FL420 or is there some kind of error on both my GPS and the IFE data? I thought the service ceiling of the 738 was 41,000 ft, and plus with a south easterly track, shouldn't we be cruising at odd flight levels?
Enroute Darwin to Melbourne on T25 just before SAPED and 475 NM from Melbourne .. at 42,000 ft?
The moving map display of my Garmin 96C showing waypoints inbound into Melbourne on H119.
Enroute Darwin to Melbourne on T25 just before SAPED and 475 NM from Melbourne .. at 42,000 ft?
The moving map display of my Garmin 96C showing waypoints inbound into Melbourne on H119.
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a) I doubt that any professional crew in Australia would fly above the aircraft's max altitude (I have no idea what the 737 max altitude is but I assume it is FL420 or above)
b) Non-standard levels are allowed in Australian airspace
b) Non-standard levels are allowed in Australian airspace
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Max operating Alt on a 7378 is FL410. However, that's a pressurization limit and not a physical limit so I'd say that you were obviously flying unpressurised to get up into a good tailwind.
As for the IFE...Flight tracking is a costly optional extra so some low cost airlines just display the same info on every flight much like a tv test pattern. As most people don't pay attention they dont realise that their East coast flight is depicted as a return flight from Bali.
As for the IFE...Flight tracking is a costly optional extra so some low cost airlines just display the same info on every flight much like a tv test pattern. As most people don't pay attention they dont realise that their East coast flight is depicted as a return flight from Bali.
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Most of the GPS units that I've played with (no barometric feed) aren't very accurate with the altitude. I think it has something to do with the geometry of the satellites, ie. the satellites used are usually fairly vertical & therefore the angle is too acute for accurate altitude measurement?!..Bueller..
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My Garmin's GPS reading is as good as 100% accurate atleast up to 15,000ft that I know of. Pretty sure I've been to 43k in a VB738 as I was thinking it was mighty high at the time considering the QF ones only seemed to be 30-35, assumed at the time it was the new 800 modelmaking the difference.
Could have been at FL410 on 1013hpa. The GPS data shows actual elevation above MSL without the errors induced by being on 1013 and density variations. Does the IFE take ADC altitude input or pure GPS signal(no baro aiding)?
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I can assure you that you weren't at 420, or 430. As pointed out earlier, 410 is a limit set to retain the 8000 ft cabin pressure at max differential. It will climb higher, but an 800 is thrust limited up that high, and we don't have too many test pilots where I work. At least not that I've flown with anyway. As for why the error? F@cknows! 43 Inches may well have it right.
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After following the AF447 accident on another thread, I have to ask the question, should I feel nervous at a height aleast approaching the service ceiling? and in this case appearing to go beond it. Would there be implications of getting too close to "coffin corner"?
I know each design is different and weights and so on, but 42k is way up there. I dont fly the big shiney jets and rarely get higher than 14k, so untill reading about AF447 I had not given "coffin corner" much thought. What do you think?
I know each design is different and weights and so on, but 42k is way up there. I dont fly the big shiney jets and rarely get higher than 14k, so untill reading about AF447 I had not given "coffin corner" much thought. What do you think?
Most definitely FL410 with the subsacle to 1013 hpa.
My only question is how on earth you got away with operating GPS inside the aircraft?
In my previous mob, the ladies behind the door would have had your drawn & quartered if they had of caught you, followed by being meet at the gate by your friendly police man.....
My only question is how on earth you got away with operating GPS inside the aircraft?
In my previous mob, the ladies behind the door would have had your drawn & quartered if they had of caught you, followed by being meet at the gate by your friendly police man.....
Typical clowns up the back, do you not listen when you are told electrical devices such as radio receivers and GPS units are prohibited at all times during the flight?
I bet you went home and flew the sector yourself on FSX patting yourself on the back thinking you could do a better job.
As for your GPS, it's not TSO approved so any information you receive is irrelevant.
On a side note, pretty light load if it's anywhere near FL410, who is bleeding money?
I bet you went home and flew the sector yourself on FSX patting yourself on the back thinking you could do a better job.
As for your GPS, it's not TSO approved so any information you receive is irrelevant.
On a side note, pretty light load if it's anywhere near FL410, who is bleeding money?
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Originally Posted by The Green Goblin;
I bet you went home and flew the sector yourself on FSX patting yourself on the back thinking you could do a better job.
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Typical clowns up the back, do you not listen when you are told electrical devices such as radio receivers and GPS units are prohibited at all times during the flight?
Correct me if I'm wrong:
What is the risk of having a unit which recieves line of sight signals but does not transmit anything back?
From memory they say "radio transmitters". They never said anything about GPS units. Brings me to the point, they say you may use your mobile phone in flight if it is in Flight/Offline mode.
Flight Mode blocks any signal being transmitted, however, the GPS unit can still "hear" the signals sent by satellites to it.
Pyro,I suggest you have a ride as a clown down the back sometime
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Use of Mobile Phones in flight
" The use of mobile phones or radio transmitting devices is prohibited during flight"
"All mobile phones should now be switched off. Those having a flight mode should be switched to flight mode prior to being turned off"
Pyro, I can tell you where to get a red rubber nose and big floppy shoes if you want them.
"All mobile phones should now be switched off. Those having a flight mode should be switched to flight mode prior to being turned off"
Pyro, I can tell you where to get a red rubber nose and big floppy shoes if you want them.
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I'm with crew rest. The GPS would be providing true altitude. Plus any anomalies in the GPS altitude, you should be able to come up with a 1000 ft error somewhere.
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well i am going to back pyro up on this one..... there is no problems in using rx devices on the aircraft (GPS, ipod, etc).. Transmitting devices thats another story!.... Green Goblin i think before you start calling pax clowns maybe you should think that those clowns are the ones keeping you in a job....also maybe they should ban laptop's as well becuase i am sure that when people use them in cruise the forget to turn off there wireless adaptor
..food for thought
Krispy
..food for thoughtKrispy
This thread has to take the prize for the biggest load of drivel on here for some time!
Its kinda hard to believe that people who pretend to be connected to the sharp end of aviation can be so WRONG!
Must be a better unit that mine (any of them)! It is not uncommon for the "altitude" display on the GPS (eg 496) to differ from the altimeter by maybe up to 500' - I have had them up to FL180!. If the Boeing was at FL410 then I am not at all surprised that the GPS might say 42.03. It is pure co-incidence that it looks so close to FL420.
That all makes sense to me!
You can't be serious, surely! If so, I hope you are never driving anything that I am a pax on.
The briefing actually says "radio transmitters" not "receivers". GPSs are passive units that receiver a signal and transmit NOTHING but the very low level electromagnetic radiation that you might expect from any electrical device. I suspect far less than the average laptop - particularly if its Wi-fi is left on!
That may be technically true but in 500+ hrs of having a non-TSO'd G296/496 alongside a TSO'd G430, I have never seen them differ by anything other than a very small margin.
....and exactly which part of a GPS is a mobile phone or radio transmitting device?
Spike, you obviously have experience with buying clown gear huh?
I think it must now be pretty common for 'clowns down the back' to use GPSs, as the trolley dollies dont seem to react as they once did. The first time I had one (with the antenna suctioned cupped to the window) on a Qantas 737 the following conversation ensued:
TD: Excuse me Sir, what is that?
Dr: Its a GPS!
TD: Sir, I don't think its permitted to use that on board an aircraft.
Dr: As far as I know it is, but I will turn it off if you wish. Could you please ask the Captain if its OK to use a GPS.
TD: OK, give me a few minutes.
Returns
TD: Sir, the Capt says it is OK to use a GPS while the aircraft is in the cruise but we require it to be turned off prior to descent, as we do for all portable electronic devices.
Dr: OK, no worries.
Smart guy that Captain - maybe that how he got to the left seat!
Dr
PS: My understanding is that the difference between the 'altitude' display on the GPS and that on the altimeter, whether set to QNH or 1013, is the datum to which each is relating.
Its kinda hard to believe that people who pretend to be connected to the sharp end of aviation can be so WRONG!
My Garmin's GPS reading is as good as 100% accurate atleast up to 15,000ft that I know of.
Could have been at FL410 on 1013hpa. The GPS data shows actual elevation above MSL without the errors induced by being on 1013 and density variations. Does the IFE take ADC altitude input or pure GPS signal(no baro aiding)?
That all makes sense to me!
My only question is how on earth you got away with operating GPS inside the aircraft? In my previous mob, the ladies behind the door would have had your drawn & quartered if they had of caught you, followed by being meet at the gate by your friendly police man.....
Typical clowns up the back, do you not listen when you are told electrical devices such as radio receivers and GPS units are prohibited at all times during the flight?
As for your GPS, it's not TSO approved so any information you receive is irrelevant.
" The use of mobile phones or radio transmitting devices is prohibited during flight"
Pyro, I can tell you where to get a red rubber nose and big floppy shoes if you want them.
I think it must now be pretty common for 'clowns down the back' to use GPSs, as the trolley dollies dont seem to react as they once did. The first time I had one (with the antenna suctioned cupped to the window) on a Qantas 737 the following conversation ensued:
TD: Excuse me Sir, what is that?
Dr: Its a GPS!
TD: Sir, I don't think its permitted to use that on board an aircraft.
Dr: As far as I know it is, but I will turn it off if you wish. Could you please ask the Captain if its OK to use a GPS.
TD: OK, give me a few minutes.
Returns
TD: Sir, the Capt says it is OK to use a GPS while the aircraft is in the cruise but we require it to be turned off prior to descent, as we do for all portable electronic devices.
Dr: OK, no worries.
Smart guy that Captain - maybe that how he got to the left seat!
Dr
PS: My understanding is that the difference between the 'altitude' display on the GPS and that on the altimeter, whether set to QNH or 1013, is the datum to which each is relating.
Last edited by ForkTailedDrKiller; 20th Jun 2009 at 05:18.
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Ok, fair enough but I'm just interested in why. As others have said, the GPS would be measuring true altitude above MSL and not FL above the 1013.25 hPa pressure level which I think is a good explanation.