Delta DC-9's

[Gorditas]

Does the descent computer just tell you how far out (nm) to start descending using groundspeed and how high you are or is it more that that?

We don't have any actual ground-speed readout. It is purely based on zero wind conditions, mileage, and 6-1 above FL290, and 3-1 below. You have to make adjustments based on wind. There are several scales on it for -30/-40 series A/C (all retired last year) -50 series A/C, and with wing A/I on. (needing some power in the descent) It is double sided with inner and outer scales. Honestly, the people who came up with devices like these amaze me. Getting a purely mechanical device to do precise calculations is a pretty neat feat.

 

[ATLplt]

Getting a purely mechanical device to do precise calculations is a pretty neat feat.

Speaking of neat feats...the first time I sat in the 717 I gazed in puzzled amazement at the utter complexity of the window mechanism for a good five minutes. I'm still in awe of the engineers who created that contraption.

 

[Cobraair75drvr]

Having never flown the 9 (lots of hours in jumpseat), I always thought the wiz wheel thingy was a little overkill. Why not just use 3:1 and adjust for wind like almost every other plane.

We don't have any actual ground-speed readout. It is purely based on zero wind conditions, mileage, and 6-1 above FL290, and 3-1 below. You have to make adjustments based on wind. There are several scales on it for -30/-40 series A/C (all retired last year) -50 series A/C, and with wing A/I on. (needing some power in the descent) It is double sided with inner and outer scales. Honestly, the people who came up with devices like these amaze me. Getting a purely mechanical device to do precise calculations is a pretty neat feat.

 

[Lucky Strike]

Having never flown the 9 (lots of hours in jumpseat), I always thought the wiz wheel thingy was a little overkill. Why not just use 3:1 and adjust for wind like almost every other plane.

3:1 doesn't work on the -9. To hold pressurization while descending aboving FL290, you can't go to flt idle. Only flt idle below FL290, and then it's 2:1.
I thought the same thing when checking out on it, but 3:1 really doesn't work...on -9.

 

[nwaredtail]

IF you need to GPS to fly a DC-9, you won't be flying the DC-9. Easiest jet to manage IMO. 6 to 1 from 350-290, 2 to 1 to 10k, 3 to 1 10k and below plus the fudge factor. Used speedbrakes once a month if I was yackin. Bye Bye DC-9

 

[nwaf16dude]

Coolest DC9 feature...the over the shoulder compass and mirror combination. The mirror comes in handy for checking out chicks

 

[wings421]

Coolest DC9 feature...the over the shoulder compass and mirror combination. The mirror comes in handy for checking out chicks

When I checked out on the -88 I thought they were pulling my leg when they told me that the compass was behind me and I had to use a mirror. How did that ever get certified???

Same way with the lie flats on the 777. The first time I sat in first and the FA came over before landing and said my seat wasn't erect enough for my airbag to deploy, I about laughed her off the jet thinking she was being funny. I didn't think anything more about it until we got the lie flats on the ER several months later and watching the training videos - there sure are airbags!

 

[airplane wizard]

So, how do you figure out what rate of descent you need for a 3:1 or 2:1 ratio? I heard a rule of thumb of altitude*3 gives you how far out in nm to start down??

 

[dicko]

So, how do you figure out what rate of descent you need for a 3:1 or 2:1 ratio? I heard a rule of thumb of altitude*3 gives you how far out in nm to start down??

Perhaps a change of your screen name would be in order ?

 

[Rough67]

If I'm at FL330 and get cross TWINS at 110 and 250 you get this: (6 to 1)
330 - 290 = 4000 .. 4 * 6 = 24 miles. ; (3 to 1) 290 - 110 = 18000 ... 18 * 3 = 54 miles . ; 24 + 54 + 4 (for slow from 300 to 250) - 10 (for avg 50kt headwind for example) equals 72 .... So start descent 72 miles from twins.. (some guys may use 2 to 1 but I think 3 works better for the diamond elite HVC happiness)
Oh .. And do that every few thousand feet on the way down to check progress


Edit: oh and if you are in icing conditions or anticipate it, that changes things too