Questions Regarding Maneuvers

[SCBearden]

Greetings,
I am a screenwriter - feature-length film (non-doc) - and as such I am conducting research in an attempt to accurately flesh out an action sequence. Two questions have I regarding (I believe) flight maneuvers. Please forgive my complete ignorance of all things aviation...
Q1) If one has a published ground track and speed of a given a/c along said track but lacks the altitude can a discrepancy between the speed and distance travelled be interpreted as a change in last known altitude?
Q2) A commercial heavy enters a 60deg turn at 430 knots, exits the turn one minute later at 350 knots and within two minutes has accelerated to 500 knots can any reasonable assumption be made regarding altitude fluctuations of the a/c in question?
Hopefully, my questions are clearer than mud as I am not quite sure how to reconstruct the imagry swirling about within this flight-ignorant brain pan.
Any assistance will be greatly appreciated,
Stephen

[justathought]

A1/ No
A2/ No


If I understand you right....there are your answers. The reason is that you don't know what the pilot is doing...how is he/she flying the plane, for all you know they could be adjusting power settings and not changing height at all.
About the only thing you could tell is that at 430 knots and turning one degree per second the bank angle of the plane would be around 16 degrees.
Give us the exact scenario and we'll try to be more helpful....eg why haven't you got a height read out from the transponder anyway??? Have the baddies turned it off???
:ooh:

[SCBearden]

Thanx for the timely response - and apologies for the sluggishness of mine.
There aren't any clearly delineated antagonists per say, not in the conventional cinematic sense anyways. The a/c of my work has a properly functioning transponder which is turned on and squawking the assigned code. However, this is of little use or comfort to the current-era crew of said a/c as they and their craft - sans warning, reason or immediate knowledge - are cruising above an Earth 55 years older than the one they had departed only moments before. Technologies old and new fail to mesh resulting in the plane being marked and tracked as an intruder.
I know, numerous plot holes and tech issues are readily apparent but this work is currently quite raw - bleeding, really. Any apparent witholding on my part stems not from proprietary caginess but from something I learned years ago: energy expended on the description of a given project is subtracted from the work itself twofold. Well, that and the fact that the greater share of my aviation knowledge is derived from my experience as a passenger on all of four commercial flights. Though I did have a window seat one one of these...
Oh, yes ---- if I may return to my first question:
A 7nm segment of ground track is covered in one minute by an a/c travelling at 420 knots. If a/c moving at 420 knots for one minute only covers 4nm could this serve to indicate an altitude change? Or perhaps I should ask - is this scenario even possible?
Again, thanx much,
Stephen

[PRNAV1]

I Think I understand what you’re saying :confused:

Do you mean to say that the aircraft has maintained 420kts and climbed?
if so then yes, it is possible for the aircraft to only travel 4nm across the surface of th earth as not only has it gone across the surface in the horizontal plane but also traveled a distance vertically (Taking into acount still air conditions)...I think that's what your getting at right??

[FlapsOne]

Yes it's possible - but you need to define 'travelling at'.
At a constant groundspeed of 420kts the aircraft will always cover 7nm in one minute.
At an airspeed of 420kts the distance covered will depend on the wind effect.
Zero headwind would result in 420kts groundspeed and therefore 7nm covered in 1 minute.
A 180kts headwind (rare, but not impossible) would result in a 240kt groundspeed and therefore 4nm covered in 1 minute.
Assuming no wind, if you travelled at 420kt airspeed, but only covered 4nm ground distance simply because you were climbing, the vertical displacement would need to be in the region of 6nm or about 36000' (fag packet calculation, not heavy maths!!).
Then a rate of climb of 36000 ft per minute at a high speed would be required and that's literally rocket science!
A combination of strong headwind and high rate of climb might get into the 'possible department' - but I'll leave that to the mathematicians

[issi noho]

F1 is correct; rocket science.

However, if its a film or even a news report, I wouldn't let a bit inaccuracy put you off, after all the general public paid good money to see Die Hard 2 and the Airport series and those were rubbish; Cone of confusion still the best except for The Battle of Britain and Dave Perrin Man in the Sky of course.

BTW is it 55 yrs from now or now from 55yrs ago? If its the later, they might have Doppler Nav and an ADF where, provided the geography hasn't changed too much, they could find a suitable place to let down and continue visually to a suitable airport and throw themselves on the mercy of the authorities for having out of date charts. Is it a short film?

No expert on film matters obviously, but as a gambler I would get Nick Parks to do it in plasticine if you want an Oscar!!:)

[cwatters]

It sounds like the script has someone on the ground trying to work out what the aircraft is doing by looking at the airspeed? In which case they need to know both the airspeed and the ground speed to work out if the plane is climbing (assuming the pilot isn't messing with the throttle). How do they know airspeed if there is a compatibility issue with the electronics? If they have the ground speed from radar why can't they see what the plane is doing height wise? .

[SCBearden]

Thanx all, great help!
The crew/craft are from the moviegoers' present - say early '08 - so 2063 or thereabouts.
A better synopsis (remember, bleedin' raw) :

The year - 2008. Post-911 tensions and conflict have increased such that the world teeters on the brink of nuclear armageddon.
Against this grim backdrop --- a commercial flight - CFL2314 -departs PHX for ATL, all progressing per routine until the flight abruptly vanishes from ATC scopes - leaving no trace, no clues, nothing to assist subsequent investigations whatsoever.
On the volatile stage of global politic, certain key players of zero ethic see the flight's thorough loss as opportunity to forward agenda - and cities vanish beneath mushroom clouds.... Fade to Black
Fade In : Flight 2314 continues an uneventful climb to altitude per last clearance.
Cue the first indications of situation breakdown: instruments offer anomolous data, comm equipment offers nothing, etc...
Enter bizzare aircraft - hushed and sinister, effortlessly gliding into scene and fixes dark attention upon an unwitting 2314 - post-apoc military responding to intruder threat.....

To prevent this post from ballooning into novel size (very real possibility if I am unchecked) --- a more-informed crew is confronted with the task of communicating peaceful intent sans relevant equipment and utterly ignorant of existing intercept protocols. This is attempted through purposeful maneuvering of their a/c in such a way as to gain/maintain non-lethal attention of pertinent parties - much in the manner bees use patterned flight to convey messages. Hence my interst in the depth/degree of interpretation possible with little more than primary track
available. The referenced 4nm segment was example only - no stone carving here, for sure. Is there a method by which a (more realistic) discrepancy between ground speed and distance travelled can be used to extrapolate altitude change?

Thanx,
Stephen

[benhurr]

My 2p...

60 years is not far enough into the future. They would squark 7600 for radio failure and broadcast on 121.5.

We are still using equipment and procedures from 60 years ago so why would there be a radical change in the next 60 years?

d=st

We have distance travelled, we have ground speed and we have time so there can be no discrepancy to extrapolate. Maybe if you lost a variable that might help.

(edited for spelling)

[issi noho]

Spent so much time telling you the answer to the question was a big fAT NO forgot to help you out of the hole.

I think the answer is pressure; 50 years there is bound to be a pressure diff, the auto pilot would adjust to the new level and auto throttle would provide thrust; pilots sit there saying whats it doing now or poss so distracted by comms/intercept might not even notice.

Hope it helps, good luck

[BEagle]

"Q1) If one has a published ground track and speed of a given a/c along said track but lacks the altitude can a discrepancy between the speed and distance travelled be interpreted as a change in last known altitude?"

Quite possibly. Let's say the a/c is flying at an Indicated Air Speed of 280 kts and is flying in an International Standard Atmosphere condition at 35000 ft. A tail wind exists of 30 kts.

It will have a True Airspeed of 488 kts, giving a groundspeed of 518 kts.

However, it then descends in the next 7 minutes at 3000 ft/min to 15000 ft where there is a tailwind of 15 kts. At the same Indicated Airspeed it will now have a True Air Speed of 347 kts and a groundspeed of 357 kts.

All the ground observer without a height readout will have seen is a 31% reduction in groundspeed.


"Q2) A commercial heavy enters a 60deg turn at 430 knots, exits the turn one minute later at 350 knots and within two minutes has accelerated to 500 knots can any reasonable assumption be made regarding altitude fluctuations of the a/c in question?"

At 28000 ft and 280 kts Indicated Air Speed, the 'heavy' would have a True Air Speed of 432 knots. If it reduced speed in the turn to 240 kts Indicated Air Speed and descended to 25000 ft (quite feasible) it would then have a True Air Speed of 349 knots. To achieve 500 kts True Air Speed in the next 2 minutes, assuming it has a maximum permitted speed of 310 kts Indicated Air Speed or Mach 0.86 (whichever the lower), it would have to climb to 33000 ft and accelerate to 310 kts Indicated Air Speed. A climb rate of at least 4000 ft/min which isn't very likely, unless it was very light indeed!

[Slasher]

If my memorey serves right the original "Commercial-Heavy-In-Flight-When-A-Nuke-War-Erupts" was a novel published in the early 80s called "Down To A Sunless Sea". Involved an 'Air Britain (?)' 797 (equiv to a 747-800I), a trashed Russian turboprop piloted by 2 horney-lookin Russki chicks (one of which the pommy skip bedded), and a trip for both aircraft from the Azores to McMurdo. The aviation and nuke sciences were completely stuffed as was the basic physics, and the storey had a real bummer ending.

Maybe SCBs will be a little more credible.