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View Full Version : Rate of Descent Formula, Part I


your_dreamguy
23rd Oct 2006, 03:58
Hello,
I think the Rate of Descent for any airplane is: ROD = (33000 * Deficient Thrust) / Weight
Is this correct? If not, what are you showing? :ok:

Re-entry
23rd Oct 2006, 12:40
What are you drinking? I must try it.

Fliifast1
23rd Oct 2006, 13:53
The green TOD says when...the green bannana says where I hit!

Ignition Override
25th Oct 2006, 07:37
Your_Dreamguy: You won't find too much help on Pprune if you decide to "invade" Europe for a civilian pilot job. The US has not be very open about hiring foreign pilots, although I've met a number of them over here. Information and dis-information is quite common on Pprune. But think about the mostly very high tax structure.
The rating conversion might be a very complex and expensive experience. If you are from there it should be much easier.

As for new gizmos, in a "classic" 60's jet, we have no 'T.O.D.' symbol or a 'green banana' .

Automation is the cure?
Sheer coincidence, but in German, the word "Tod" means death. Automation: Cali, Habsheim, Mulhouse, India, Toulouse, the Gulf.
Almost, near Las Vegas.
Always rely on your automation ( the buttons are the Captain). That is what the book says. The book pages shall protect us from cloud-covered granite walls, tranquil white-capped ocean.

One night over water or mountains, the IRS systems, the FMC or the displays might fail. With an APU deferred per MEL then a strange bus tie problem, the equivalent of an "AC crosstie lockout"?
OK-it can not happen.... so stated the 'experts' in the Pentagon.
I can tell you about three near-disasters in four-engine C-130s in which all AC generators were lost for a while. My father suffered two (their lives were twice saved by highly-experienced, very professional Flight Engineers!). An A- an E- and a B-model (over Hawaii) had these frights: all were in nightime IMC. One crew in Hawaii extendd the gear and came thru an undercast. The older C-130s still have no standby ADI! How about the Zantop "Logair" Lockheed Electra over Utah...very bad scene.:ouch:

:D To descend, we mostly double the altitude we must lose, then add 10-20 miles, depending upon weight, tailwind and whether we can keep the cabin descending with airfoil anti-ice on, at idle power-easier nowadays with digital pressurization.
But this is the only digital apparatus in the 'classic' airplane, except for fuel gauges. Our two-person c0ckpit requires lots of manual manipulation, having been built before LNAV and VNAV were dreamt of. Plus or minus a good ACARS.

WindSheer
25th Oct 2006, 07:59
Ignition Overide, thanks for your enditement upon why not to rely upon the the little 'dot of snot', but would you care to enlighten us into your method of descent??

All the best! :suspect:

Ha ha. Only kiddin me old mucka!
Your double and add 10- 20 would leave you high in most modern jets I believe? With it being more of a case of treble it and add 10.

I stand to be corrected though!!

Ignition Override
25th Oct 2006, 08:13
You got me there, but we mostly just double the altitude and add 10-25 miles, depending on possible winter tailwind, even with the slick new pressurization (now digital!). In the dash 50, we might triple the altitude to lose. I'm just a bit lazy, can't speak for the others.

Except for VOR/LOC/GS-capture, without automation in a 100-122 seat two-person c0ckpit (even with the now fairly tight airfoil pneumatic system), we are too busy to worry or care about making the altitude and/or 250 knots with just a few miles to spare, in a general sense, flying three different series of Jurassic "steam-gauge"/'water-klok' planes.

TriStar_drvr
25th Oct 2006, 15:56
In the TriStar it was triple the altitude then 2 miles for each 10 knots of wind. Example: 34,000 feet to lose with a 50 knot headwind = (3 X 34) - (2 X 5) = 92 miles prior. Of course add the correction for a tailwind.

Now I'm on the 737 NG so I just use the green dot and banana, although I do the math just to back it up. Never know when I might have that triple generator failure :rolleyes: (see other thread)!