Small quiz!

[Guest ilh]

Let's see, you'd lose TAS and wind direction/speed on the ND, right?Lee Hetherington (KBED)http://www.precisionmanuals.com/images/betaimg.jpg

[Guest Bjorn Ghezzi]

To know your altitute above 2500' ask ATC. :-))Regards,Bjorn

[Guest Mark McG]

Hi jeff,yeah, it's in a book I got as a gift of Cockpit Voice recordings. One of the most remarkable is the United DC-10 at Sioux City.

[marcom 139]

Right on!Both indications would show rediculous data. I have seen wind indications (in this situation) of a 300 kts tailwind :-)A very strong jetstream at 3000 ft :-)Mark

[JRBarrett 3,046]

>Hi Mark!>>Regarding a)>>"Airspeed fails to Increase as you acclerate during the TO>Roll.">I don't want to give out the precise answer yet, but that's>not the only clue. It would be if your pitot was stuck, but>not if your static is blocked.>If the static ports are blocked, the altimeter will "freeze" at whatever altitude it was indicating at the moment the blockage occured.At the same time, the airspeed indicator will start acting like an altimeter. Assuming actual true airspeed remains constant, indicated airspeed would drop as the aircraft climbs above the altitude where the blockage occured, and would increase as the aircraft descends.If the aircraft climbed high enough, indicated airspeed would drop to zero, even if the aircraft is actually moving a high TAS.By contrast if the static blockage took place at a high altitude, IAS would eventually increase beyond redline as the aircraft descended, even if it were (somehow) standing still and not moving forward at all.Jim Barrett

[marcom 139]

Aha, but your altimeter encoder, which the transponder uses to send altitude data to ATC, uses the same erroneous data. Therefore, it is extremely important to notify ATC that the altitude they see you at is wrong and that you can not confirm your altitde so that they clear all traffic away from you.Regards,Mark

[marcom 139]

Correct!You could even get a negative airspeed :-)Also, during final approach you have to count with the overspeed warning going off.Mark

[Guest ilh]

That makes perfect sense. If you had a GS of 300kts and a IAS=TAS=0, the computer would assume you are a hot air balloon with all your GS coming from a tailwind. Not exactly the correct conclusion.Lee Hetherington (KBED)http://www.precisionmanuals.com/images/betaimg.jpg

[Guest keith_yingling]

Yes, in a thrust producer the fuel flow=thrust required=drag. Just look at the graph and a specific fuel flow will give you 2 airspeeds..1 in the region of normal command (above minimum drag) and 1 in the region of reversed command. Just remember that the graph shifts with weight changes, configuration changes, and altitude changes. For a climb I suppose you can use the equation RC=101.3*V(Ta-Tr/W) and solve for V. Or you could just shoot for maximum climb angle (which occurs at minimum drag) and use that airspeed.Im not sure if this is what they would really do. Im just using my basic knowledge of aerodynamics.Keith Yingling

[Guest keith_yingling]

I knew a guy that was in that crash. He was sitting near the section that split off. He survived but the two people next to him didnt. He rolled 300 yards beside the runway in the grass. he said the only thing he remembered was a big fire ball coming toward him. Didnt wake up for several months. He's a millionaire now, of course.Keith

[marcom 139]

In these types of situations, any equation a pilot has to calculate would not be very helpful.All I know is that the table provides a N1/pitch attitude for a given weight for a specific phase for a specific altitude.A resulting error should be pretty small, as you already have to interpolate between different weights and thus the N1 won't be 100% correct. Of course, you won't be able to maintain 0 VS even if you did set the N1 100% correctly and fly the exact pitch attitude as you still have to take the weather into account.But it will be precise enough not to fly into terrain and to make it to the IAF where you can fly a normal ILS approach where an altimeter is not required (of course, normally, it is required to perform the required crosschecks but in an emergency you simply have to assume that the darn thing works :-), and you still have the two ways determining altitude which haven't been covered yet :-) )Regards,Mark

[Guest Darren Howie]

G'day For altitude i think you should be able to access the ALT info from the GPS system via the FMC as position data.All IFR approved GPS's have true ALT data available via a position page.Don't know the other one though.Have fun

[marcom 139]

Exactly!That is indeed one way of getting altitude information!Now what's the other way?Regards,Mark

[Guest eker]

1. DME2. OAT 3. Start APU with bleed on - climb - check bleed cut out.eker

[marcom 139]

Hi Eker!DME would be a way, yes, but it's very unprecise. Also, you'd have to be right on top to determine altitude.OAT. I guess you mean SAT as you don't have an OAT indication. That would work, but for that you'd need the ISA deviation for the current location and you'd have to assume that there is no inversion where you currently are.I don't really understand your third proposal. Could you ellaborate on this?There is one more technique no one has mentioned yet. I'll post it later on.Mark