Airstarter and some more questions 737

[Speedwinner]

Hey folks,

Have some questions concerning the 737 Classic:


1.) APU inop. Very hot weather. We need an air starter to start the engines. The crew wants the airstarter to start earlier to put the packs and cool down the cabin. Driver doesnt want that, he says that the air is too hot he is supplying. But it works. What are your opinions and procedures?


2.) GPS is not working. We have only one GPS on board. The MEL says, we are not allowed to fly "GPS based procedures". So may we fly an RNAV overlay departure route? Not sure about that.


3.) Is it mandatory that the approach lightning system is working when its daylight and good visibility? For example when theres no electrical power? NIL? Not allowed?


4.) Have you git a quick formula how you calculate the WCA on approach?


5.) Flying with 210kts, the 737 is not really able to control this speed. 220 ok, 210 always goes around plus minus 5kts. Any idea?


6.) Why does the VNAV Mode always pitch up at FL100 and then pitch down when accelerating?


7.) Flying with FD off and AP off, ATHR armed. in the ALT window is 4000 feet and we are at 5000ft on the glideslope. Approaching 4000ft the ATHR just puts in some thrust. Why?




Thanks friends!

SW

[Cough]

2) our 737's don't have gps, yet do fly prnav procedures.

5) coz it's crap.

6) ditto. Don't worry

7) because the auto thrust has just entered speed mode in order to capture 4000'. It isn't clever enough to know that you don't want to maintain that level. It's similar to it entering low speed protection at 60' and then going retard soon thereafter because it thinks you are autolanding. I used to have auto thrust armed every approach in case of a ga, but disconnected it any time it entered low speed prot on the approach below 200'.

Oh and 1. Does work, but shortens the life of the air start units. Hence they aren't keen!

[BOAC]

Picking up on 1) only:

It works well because it is supplying high pressure air to the packs, which is how they work, and THEY produce the cooling - next time ask the 'Driver' what temperature he thinks the engines are supplying to the packs.:)

As Cough says, there are problems with load on the unit. If you have a diesel driven air start it can only run for a minute or so at full power and so is not worth trying. The turbine powered unit however is a different prospect and can run for a significant time at delivery power. I have successfully used the latter to cool a hot cabin on several occasions..

[NSEU]

Driver doesnt want that, he says that the air is too hot he is supplying. But it works. What are your opinions and procedures?


Seems that the driver already gave you his ;)

Incidentally, he may not necessarily have known the aircraft's temperature limitations. However, most likely, he will have been given instructions on the start cart's use and will have been trying to abide by those instructions.

In this case, the air had to be put on at some point, so it appears it's not out of laziness he didn't want to do it (Is this what you were inferring from his response?).

Ground staff and air staff sometimes have procedures which conflict. You won't necessarily solve them by insisting on something/pulling rank. You will still have the same problem with the next guy. You need to go through the appropriate channels to resolve this kind of thing, especially when neither of you have time to "debate" the issue on a quick turnaround. Who knows, perhaps the company might decide to buy you a shiny, new, temperature tolerant external air supply unit and everyone will be happy ;)

Rgds

[ampclamp]

You run a diesel or elec bridge mounted unit for elec pwr AND the apu for air and you save greenhouse gas ?

[NSEU]

You run a diesel or elec bridge mounted unit for elec pwr AND the apu for air and you save greenhouse gas ?

Me? No. For greenhouse gases, we are told to turn off the APU ASAP and use only external sources (where available). I believe there are some airlines which do leave the APU running, but plug in external elec pwr only. Seems like a lot of bother for a few kilos of carbon when the engineers' time could be better spent elsewhere (refuelling, fixing defects, etc).

Turning off the APU completely, however, helps the environment and helps the airlines bottom dollar and, as someone commented to me, culls off the older, more highly paid ground staff with back complaints :}

[ampclamp]

hi nseu,
I think my post was edited somehow.?
the intent was not query you but to highlight the silly practices of the airline I work for of doing just that.Run a power unit (elec or diesel) to supply elec power to the ship plus run the apu for air.
Considering the labour cost (and possible injuries) the fact that our elec power is derived from coal fired power stations and the diesel units puke buckets of black crud it is not exactly clear cut who wins at all.But it does allow them to trumpet their green credo by saving xyz kilos of fuel.Never mind the diesel and coal (and compo).