B737-200 TOD calculation

[FlyDouglasJets]

Ok, no VNAV in this bird. What's the thumb-rules for optimum TOD calc's (M.74/320/250kias profile)?

Wanna be @ 250kias/10,000'agl 30nm from the rwy?

FLxx - 10k = yy
yy*2 + 30nm = xy
xy + 10nm = opt TOD dist.

FL33 - 10 = 23
23*2 + 30nm = 76nm + 10nm to slow from 320 to 250kias.
opt TOD = 86nm

What's the HeadW/TailW correction? +5/-5nm per 50kts TW/HW?

Thanks,
TD

 

[TR4A]

320 KIAS = 2 nm/1000'
280 KIAS = 2.5nm/1000'
250 KIAS = 3nm/1000'
For every knots of wind add or subtract 1nm

FL330 - 10,000ft = 23,000 to descend @ 320kts = 46nm + 7 miles to slow to 250 (1nm/10kts).

With 50 kts tailwind add 5nm

Total 53nm plus the 30 nm from the airport.

83nm from airport.

I normally use 35 miles 250kts @10,000

 

[ParrotheadPilot]

We generally use:

23,000 feet to lose is 23*3=69 nm

70 knots of airspeed to lose at 1 nm per 10 knots=7 nm

69+7=76 nm from airport.

TR4A is absolutely correct with adding 5 nm for a 50 knot tailwind

 

[jeff333]

Ok, no VNAV in this bird. What's the thumb-rules for optimum TOD calc's (M.74/320/250kias profile)?

Wanna be @ 250kias/10,000'agl 30nm from the rwy?

FLxx - 10k = yy
yy*2 + 30nm = xy
xy + 10nm = opt TOD dist.

FL33 - 10 = 23
23*2 + 30nm = 76nm + 10nm to slow from 320 to 250kias.
opt TOD = 86nm

What's the HeadW/TailW correction? +5/-5nm per 50kts TW/HW?
Thanks,
TD

Man way too much work. Use 3 to 1 as a good rule. If you have a major tailwind start down a little early. The wind will make some major changes at times on the way down. Add about 7 miles to slow down to 250. If your still high use the speed brake or dial up the speed. I always do a quick 3 to 1 calculation every couple thousand feet to make sure I am on profile.
Don't need no stinking vnav.

 

[KeroseneSnorter]

I Gotta agree with Jeff,

You guys are killing yourself with all those calculations....3 to 1 works perfect. Much less work, and it gives you lots of free time to scratch a pesky itch or something else useful.



(P.S. You guys don't have a complex calculation for crosswind and distance over the toilet bowl too do you? )

 

[English]

250KIAS 30NM from the runway? Why so slow?

 

[FlyDouglasJets]

Thanks for the input.

 

[F16TJ]

Chevy Chase impersonating Gerald Ford on SNL...

"It was my understanding there would be no math".

Gotta go with the 3 to 1 ratio, works like a champ.