jgore
Posts: 518
Joined: Sun Feb 17, 2002 2:41 am

Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 2:53 am

Hi

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Why would pilots set 100 kts ias in their autopilot since they land or takeoff about 130-145 kts ?.
Is this somehow useful in any phase of flight ?  Confused

Thanks in advance

Regards

Jgore  Smile
 
T prop
Posts: 912
Joined: Tue Apr 03, 2001 4:33 pm

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 4:40 am

The airplane is on the ground with both engines shut off, I imagine the autopliot is not needed in this situation.

T prop.
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 4:43 am

First of all, if those guys are inflight, they are in major trouble!! Big thumbs up
That flightdeck is not prepared for flight.They are on the ground and nothing is setup.

Anyway, inflight the mode control panel would not let you set a speed below the alpha floor limit. I think it is something like 1.3 times the stall speed.
 
jgore
Posts: 518
Joined: Sun Feb 17, 2002 2:41 am

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 5:42 am

Well, I know is not necesary when the airplane is grouded. But I doubt pilots or any mantenience guy were playing with the knob leaving the counter in 100.

Jgore  Smile
 
FBU 4EVER!
Posts: 980
Joined: Sat Jan 27, 2001 6:53 am

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 7:10 am

It's most likely a default value.At least that's how it reads on our MD-80/90 readouts when a powerchange has occurred and no pilot-selected value has been entered.
You may well set 100 kts in the readout window during flight,however,the Flight Management System will prevent the plane from decellerating below Alpha (min speed for present configuration) and the Flight Management Annunciator will show ALFA SPD and control speed to applicable value.
But things can (will) go wrong,and no pilot in their right mind would set such a low speed in the readout.
"Luck and superstition wins all the time"!
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 8:35 am

But I doubt pilots or any mantenience guy were playing with the knob leaving the counter in 100.

FBU is correct. That is the default value on the IAS/MACH window when pwr is applied
 
airplay
Posts: 3369
Joined: Sat Oct 25, 2003 1:58 am

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 10:04 am

Although it is probably not the case here, as evidenced by the well informed posts above, there is always the possibility that one of the segments on the speed display is burnt out. In other words, maybe 180 is set but 100 is displayed because the center segment of the "8" is missing.
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 10:28 am

I suspect the -700 has the same MCP as the -800.
From my AA 737-800 OpMan:
"IAS/MACH Display... Displays 100 knots when power is first applied."
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
GE
Posts: 312
Joined: Sun Mar 26, 2000 5:01 pm

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 11:19 am

It's the same for the A319/320/321.
100 knots is displayed on the Flight Control Unit when first powered up.

Regards,
Russell J.
 
jgore
Posts: 518
Joined: Sun Feb 17, 2002 2:41 am

RE: Why 100 Kts IAS On This 737 Autopilot?

Sun Dec 01, 2002 2:40 pm

Ohhhh guys, you've made it very clear enough. Thank you very much.

Jgore  Smile
 
Rick767
Posts: 2613
Joined: Sun Jan 30, 2000 8:11 pm

RE: Why 100 Kts IAS On This 737 Autopilot?

Mon Dec 02, 2002 4:39 am

Just to confirm, 100 knots is the minimum "default" value which appears in the 757/767 MCP Speed Window as well when the juice starts flowing.
I used to love the smell of Jet-A in the morning...
 
CX Flyboy
Posts: 6040
Joined: Sun Dec 26, 1999 6:10 pm

RE: Why 100 Kts IAS On This 737 Autopilot?

Mon Dec 02, 2002 5:50 pm

Not quite related, but after landing, we always set the parking bay number as a reminder in the altitude window, so if bay 1 we set 100. Bay 10 we set 1000. It not a company requirement and it not written anywhere, but more something that we just do! just a reminder as sometimes the taxying can be complicated at some airports so you don't want to forget the bay number!
 
wardialer
Posts: 1142
Joined: Fri Sep 14, 2001 1:08 pm

RE: Why 100 Kts IAS On This 737 Autopilot?

Thu Dec 05, 2002 2:40 pm

Well take a look. The PFD display is almost displayed in black, meaning that they have just turned on the APU system. Like on the MD-11, when everything is first set up, the autopilot console will automatically will show a reading of the standard IAS as 250 knots. Or it could just be in a test mode. But again on the MD-11, it will say as "Fail" on the PFD.

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