track miles to go
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Join Date: Dec 1999
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track miles to go
Dumb question time. For the purposes of descent planning, how do you calculate track miles to go? Do you relie on the controller telling you, or use some other technique?
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3 x height in whole thousands of feet, + 10 nm for deceleration from high speed for jets, +/- 1 nm per 10 kts head/tailwind. Therefore, FL 330 in 50 kts tail = 3 x 33 + 10 + 5 = 114 nm descent point from runway threshold. Right, now where's my answer about takeoff alternates; I need to go for a coffee!
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Lots of ways of working out track miles and lots of variables, and therefore lots of ways of making a potential mistake.
Variables include theterrain, weather, duty runway, time of day (how busy is it going to be) which all may mean that you will have extended vectors for an instrument approach or a straight in visual.
The safest way is to use the FMS or map to calculate the shortest route onto the rwy via the SID and transition to calculate TOD, and then modify RoD as required.
Variables include theterrain, weather, duty runway, time of day (how busy is it going to be) which all may mean that you will have extended vectors for an instrument approach or a straight in visual.
The safest way is to use the FMS or map to calculate the shortest route onto the rwy via the SID and transition to calculate TOD, and then modify RoD as required.
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vmc,
did you mean 'dist to touchdown?'
unless you know approx how the ATC is gonna vector you based on previous experience and your FMC is programmed as such, the DTG on FMC progress page seem to work for me. otherwise, i'd have to rely on the good-ole-friendly ATC
SR
did you mean 'dist to touchdown?'
unless you know approx how the ATC is gonna vector you based on previous experience and your FMC is programmed as such, the DTG on FMC progress page seem to work for me. otherwise, i'd have to rely on the good-ole-friendly ATC
SR
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if i may add on to capt sensible contribution...
1) wt. of A/C-i.e. heavier a/c slower to decel
2) use of de-icing on the descent. it will shallow out the descent
3) and if an altitude constraint is the restrictive of all these
1) wt. of A/C-i.e. heavier a/c slower to decel
2) use of de-icing on the descent. it will shallow out the descent
3) and if an altitude constraint is the restrictive of all these
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Lots of variables of course, but three times the altitude (in thousands) + 10 with wind/weight considerations , as mentioned previously, is a good place to start.
Recall some years ago flying with a new First Officer who seemed to be obsessed with the proper TOD point.
Would twist the bezel of his Breitling watch for 15 minutes then announce proudly that the proper descent point was xxx nm, precisely.
As it turned out, he was precisely wrong nearly every time..
Recall some years ago flying with a new First Officer who seemed to be obsessed with the proper TOD point.
Would twist the bezel of his Breitling watch for 15 minutes then announce proudly that the proper descent point was xxx nm, precisely.
As it turned out, he was precisely wrong nearly every time..
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If you do, however, use the 3x 33 (FL330)...etc....isn't that the top of descent point? Another thing, can the pilot decide that, yes this is where I'd like to start descending, or does he/she wait for ATC instructions?
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Fatboy Slim:
"The safest way is to use the FMS or map to calculate the shortest route onto the rwy via the SID and transition to calculate TOD, and then modify RoD as required."
Say again all after safest and via!!!
Am in picky picky mood today!
"The safest way is to use the FMS or map to calculate the shortest route onto the rwy via the SID and transition to calculate TOD, and then modify RoD as required."
Say again all after safest and via!!!
Am in picky picky mood today!
