karthikaadi
Topic Author
Posts: 2
Joined: Sun Jun 03, 2012 1:12 pm

Speed Loss In Turboprop During Approach

Mon Jun 04, 2012 1:16 pm

Hi,

Could anyone who has or is flying a Turboprop like dash 8 or ATR, tell me if its possible to lose close to 100 kts when you are trying to configure the aircraft for ldg (CL Max, Gear Down, Flap 15) on a final approach in an ILS after established on the ILS fully, and power levers to Flight Idle (initially) as IAS greater than 220. this happened to me and just wanted someone's opinion as well. the best part is all this in 30 secs (about a mile and half of distance lost).

Thanks
 
DashTrash
Posts: 1266
Joined: Mon Aug 21, 2006 8:44 am

RE: Speed Loss In Turboprop During Approach

Mon Jun 04, 2012 1:28 pm

Yes it is. Going from 900 to 1200 RPM in a Dash 8 is like opening a parachute if you don't increase Nh (advance power levers). It's a two handed operation. PNF advances the props, PF advances the power.
 
JBirdAV8r
Posts: 3454
Joined: Sun Jun 24, 2001 4:44 am

RE: Speed Loss In Turboprop During Approach

Mon Jun 04, 2012 1:29 pm

Quoting karthikaadi (Thread starter):

Hi,

Could anyone who has or is flying a Turboprop like dash 8 or ATR, tell me if its possible to lose close to 100 kts when you are trying to configure the aircraft for ldg (CL Max, Gear Down, Flap 15) on a final approach in an ILS after established on the ILS fully, and power levers to Flight Idle (initially) as IAS greater than 220. this happened to me and just wanted someone's opinion as well. the best part is all this in 30 secs (about a mile and half of distance lost).

Thanks

Sure! It's much easier to do this in a turboprop than a jet (actually that's just about impossible in any jet I know). When you put turboprop engines at idle, you've got two huge propellers creating an unbelievable amount of drag. They get you slowed down in a hurry.

It's easy, safe, and done all the time! It can really help ATC resolve spacing issues.
I got my head checked--by a jumbo jet
 
Woodreau
Posts: 1336
Joined: Mon Sep 24, 2001 6:44 am

RE: Speed Loss In Turboprop During Approach

Wed Jun 06, 2012 6:24 pm

Very possible in a turboprop, I've gone from 245-248kts to Vapp-115kts - starting configuration under 1500ft AGL while remaining on localizer and descending on the glidepath and fully configured and meeting VFR stabilized approach at 500ft AGL.

The two regional jets I have flown EMB-145 and CRJ-700 will also do the same thing although not starting as low. Usually starting configuration at 2000ft AGL (maybe 1700-1800ft AGL at light landing weights with a head wind - at heavier landing weights and or with a tailwind you'll need to start configuration at a higher altitude) starting your configuration at 230kts (CRJ-700) or 250kts (EMB-145), you can remain on localizer and continue the descent on the glidepath at flight idle without using speedbrakes to be fully configured on Vapp speed and on glidepath at 500ft AGL.

About the only thing more fun is decelerating a 10,000 ton destroyer from a Vmo of 30kts to a complete stop in 1,500ft and 65 seconds and watching everything that is not secure for sea going adrift.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
MGASJO
Posts: 344
Joined: Sat Feb 12, 2005 9:37 am

RE: Speed Loss In Turboprop During Approach

Wed Jun 06, 2012 6:37 pm

With a Caravan you can do an approach easily at 160 kts and bring the power to idle and you will be at 90kts in about 4 seconds, provided you compensate properly. We do it all the time in SJO at nights, when they squeeze us between larger jets and ATC ask us to keep 150 kts on the approach...Feels exactly like opening a parachute!
C208B
 
karthikaadi
Topic Author
Posts: 2
Joined: Sun Jun 03, 2012 1:12 pm

RE: Speed Loss In Turboprop During Approach

Thu Jun 07, 2012 12:57 pm

thanks all for your reviews, i started flying the dash 8 a few months ago, since am a toddler i wanted to know if this can be done, i think this is a great aircraft to play around with, not sure if other aircrafts can do this. How about the ATR 72's? is this possible in that as well?
 
flight152
Posts: 3251
Joined: Fri Nov 24, 2000 8:04 am

RE: Speed Loss In Turboprop During Approach

Thu Jun 07, 2012 4:21 pm

Quoting karthikaadi (Reply 5):
i started flying the dash 8 a few months ago

If this was the case, wouldn't you already know the answer?
 
Dufo
Posts: 799
Joined: Tue May 18, 1999 2:41 am

RE: Speed Loss In Turboprop During Approach

Sat Jun 09, 2012 8:46 am

It is possible. From 6 miles final and 245 kts I can start reducing speed and be configured at 500ft AGL, 110 kts.
I seriously think I just creamed my pants without any influence from any outside variables.
 
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Francoflier
Posts: 4071
Joined: Wed Oct 31, 2001 12:27 pm

RE: Speed Loss In Turboprop During Approach

Sat Jun 09, 2012 9:00 am

Those huge propellers pretty much turn into solid flat discs when you kill the power and decrease the pitch.

Some engines don't particularly appreciate negative torque, however. Read you manual before coming in like a burning meteor on 5 NM final...
 
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
alasizon
Posts: 912
Joined: Sat Apr 28, 2007 8:57 pm

RE: Speed Loss In Turboprop During Approach

Sat Jun 09, 2012 10:52 pm

I often have flown a very short approach into LWS in a Q400 on QX and I know we are at 220 at a 4.5 mile final. Often we are at 245 6.5 miles out and then we make a set of turns then have one more turn at 3mi (only on a certain approach, the rest are lined up about 8mi out)
Customer Operations Manager & Tower Planner
 
LimaFoxTango
Posts: 817
Joined: Wed Jun 16, 2004 11:33 pm

RE: Speed Loss In Turboprop During Approach

Sat Jun 09, 2012 11:39 pm

Quoting karthikaadi (Reply 5):
i started flying the dash 8 a few months ago
Quoting Flight152 (Reply 6):
If this was the case, wouldn't you already know the answer?

This is something new Dash 8 pilots would be very cautious about doing as it can go very wrong very quickly.
You are said to be a good pilot when your take-off's equal your landings.
 
sprout5199
Posts: 1681
Joined: Sat Feb 26, 2005 8:26 am

RE: Speed Loss In Turboprop During Approach

Mon Jun 11, 2012 7:40 pm

Quoting woodreau (Reply 3):
About the only thing more fun is decelerating a 10,000 ton destroyer from a Vmo of 30kts to a complete stop in 1,500ft and 65 seconds and watching everything that is not secure for sea going adrift.

Ahh a crash back. I remember them well. Nothing like being on the flight deck of an FFG doing one with the stern jumping up and slamming down. Kind of breaks stuff.

Dan in Jupiter

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