Go Back  PPRuNe Forums > Aircrew Forums > Flying Instructors & Examiners
Reload this Page >

Full flap at 500ft in a C152?

Flying Instructors & Examiners A place for instructors to communicate with one another because some of them get a bit tired of the attitude that instructing is the lowest form of aviation, as seems to prevail on some of the other forums!

Full flap at 500ft in a C152?

Old 14th May 2009, 19:47
  #1 (permalink)  
Thread Starter
 
Join Date: Jul 2008
Location: UK
Posts: 61
Likes: 0
Received 0 Likes on 0 Posts
Full flap at 500ft in a C152?

The CFI at my club insists on having an SOP whereby every student must lower full flap as they are turning final, typically 500ft.

I was taught (and was taught to teach!) to lower full (30 degrees) flap with 200ft to go, which has always worked fine for me and I can't say it upsets the a/cs attitude at all really - it helps to reduce from the speed from 65 to the 60kts over threshold.

I cringe inwardly whenever I see a student crawl towards the threshold all the way down finals because he has the drag flap down!

Its not a major issue so I let it slide, anyone else got any opinions on this?
darn is offline  
Old 14th May 2009, 20:20
  #2 (permalink)  
 
Join Date: Apr 2009
Location: Hotel Gypsy
Posts: 2,821
Likes: 0
Received 0 Likes on 0 Posts
Interesting. We tend to teach to avoid altering the aircraft configuration in a turn, especially base-to-final. 500ft on final also seems a bit excessive, I think 300ft is nearer the mark. However, I would offer that we should be teaching application of flap when most appropriate and not at a specific time/place/altitude. Sounds like someone who is overly hung up on flying by numbers.
Cows getting bigger is offline  
Old 14th May 2009, 20:23
  #3 (permalink)  
VFE
Dancing with the devil, going with the flow... it's all a game to me.
 
Join Date: May 2000
Location: England
Posts: 1,688
Likes: 0
Received 0 Likes on 0 Posts
Any danger of revealing where this school is? Full flap when turning base leg to final approach is going to inevitably lead to someone spinning in, simple as that.

Have you asked your CFI why he insists upon this ludicriously dangerous SOP?

I teach lowering full flap once sure of making the runway. You will look a bit silly landing short of the runway with full flap on the day the donkey dies 1 mile out.... seen it happen before.

VFE.
VFE is offline  
Old 14th May 2009, 20:25
  #4 (permalink)  
 
Join Date: Apr 2009
Location: Hotel Gypsy
Posts: 2,821
Likes: 0
Received 0 Likes on 0 Posts
I think my personal views regarding application of flap on the final turn are similar to VFE's, I was just trying to be a little more diplomatic.
Cows getting bigger is offline  
Old 14th May 2009, 20:48
  #5 (permalink)  
 
Join Date: Jun 2006
Location: UK
Posts: 21
Likes: 0
Received 0 Likes on 0 Posts
Wings level on finals works well for us.
goatmanni is offline  
Old 14th May 2009, 21:16
  #6 (permalink)  
Thread Starter
 
Join Date: Jul 2008
Location: UK
Posts: 61
Likes: 0
Received 0 Likes on 0 Posts
Its not so much the lowering full flap during the turn that he insists on, more the fact that it must be lowered so far out.

As for not lowering full flap until being sure of making the runway, thats an interesting idea ive not heard before other than when doing a glide approach. Makes sense, but unfortunatly I won't be teaching it!
darn is offline  
Old 14th May 2009, 21:33
  #7 (permalink)  
 
Join Date: May 1999
Location: Quite near 'An aerodrome somewhere in England'
Posts: 26,850
Received 333 Likes on 116 Posts
I teach lowering full flap once sure of making the runway.
Which is not particularly clever on a powered approach - you are NEVER 'sure of making the RW' until you cross the threshold, which is far too late to wait to select full flap.

Sensible SOP for any SEP is:

Roll out of final turn.
Select landing flap, trim.
Adjust IAS to approach speed, trim.
Select touchdown aim point.
Maintain aim point with control column and approach speed with throttle.

So easy - and so intuitive!
BEagle is offline  
Old 14th May 2009, 22:12
  #8 (permalink)  
 
Join Date: Feb 2007
Location: Woking, Surrey
Age: 43
Posts: 159
Likes: 0
Received 0 Likes on 0 Posts
Interesting, BEagle...

I've been taught (for VFR SEP initial training at least) to maintain approach speed with elevator and rate of descent with power...
JonathanB is offline  
Old 14th May 2009, 22:30
  #9 (permalink)  
 
Join Date: Aug 1998
Location: Ex-pat Aussie in the UK
Posts: 5,811
Received 136 Likes on 68 Posts
Power/speed/elevator/slope arguments are a different thread, and have surely been done to death!

Airlines these days require stable approaches from at least 500', and most now from 1000'. I suspect that this is where this CFI is coming from. (When I first started on jets, it was a constant deceleration approach - which is nicer to fly, but less forgiving. The stable approach is much better when considering safety over an entire fleet.)

Is it appropriate for a light aircraft? I would think that the philosophy is correct, especially for students, as it allows them to concentrate on the landing rather than the configuration.

The distance though - if it is appropriate for a 737 with 130 knot approach speed to be stable at 500', then a C150 with a 70 knot approach speed should I think, use half that - 2 or 300' would be more appropriate, I should think.

Why not put this argument to your CFI - you recognise the training value of the stable approach, and fully intend to teach it, however you feel 2 or 300' to be a more representative value of airline flying?
Checkboard is offline  
Old 14th May 2009, 23:11
  #10 (permalink)  
VFE
Dancing with the devil, going with the flow... it's all a game to me.
 
Join Date: May 2000
Location: England
Posts: 1,688
Likes: 0
Received 0 Likes on 0 Posts
Which is not particularly clever on a powered approach - you are NEVER 'sure of making the RW' until you cross the threshold, which is far too late to wait to select full flap.
Slight generalisation - should've read: "sure of making the usable runway surface"... but regardless, this particular debate regarding when to lower landing flap must surely be airfield specific?

To elaborate: The above procedure was introduced at a US institution I was with some years ago after a PA-28 fell short of the undershoot on approach following an engine failure. The NTSB investigation commented that had the pilot delayed lowering full flap "until sure of making the useable runway surface" (or words to that affect) then damage to the aircraft would have been reduced because it would not have landed on the approach lighting.

But in my experience, in the USA they try to teach student pilots how to actually fly an aeroplane whereas over here I get the distinct impression that we're encouraged to teach students merely how to cope with one. Flying exercises within the JAR PPL syllabus that actually deal solely with developing raw handling skills are sadly lacking IMHO and very soon someone here will pipe up about upsetting the aircraft configuration at the last minute being dangerous because the (basic) skills to handle it are not taught.

I do believe a certain Capt.Sullenburger will back me up here...

VFE.

Last edited by VFE; 14th May 2009 at 23:21.
VFE is offline  
Old 14th May 2009, 23:34
  #11 (permalink)  
 
Join Date: Mar 2009
Location: Perth
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
???

I can't agree with BEagle on the control inputs on final, that's just asking students to stall and die.

Power controls rate of descent, pitch controls airspeed.

Maintain final and short final airspeeds with attitude (control column) and gentle changes in power to maintain the 'aiming point' on the runway.

Works a treat for me anyway...
smudgiebottom is offline  
Old 15th May 2009, 02:08
  #12 (permalink)  
 
Join Date: Mar 2008
Location: Above the Transition Level
Posts: 160
Likes: 0
Received 0 Likes on 0 Posts
What are his reasons for this?
The other thing is some of the 150/152s have 40deg flap and this makes a huge difference esp in the event of being a little low or slow on app or if on a go around.
Totally agree that "reasons why selecting certain configs" at this stage of the game.
ElitePilot is offline  
Old 15th May 2009, 07:06
  #13 (permalink)  
 
Join Date: May 1999
Location: Quite near 'An aerodrome somewhere in England'
Posts: 26,850
Received 333 Likes on 116 Posts
The 'point and power' technique which I described is simpler and more intuitive than the old-fashioned way. It also leads to earlier solo (about 1-2 hour in most cases) - and is the way the RAF has been teaching it for about 20 years - yes, in light aeroplanes.

But most of the poorer FIC schools don't have a book to refer to and hence won't teach it as they don't actually understand the technique.

CC for IAS and throttle for RoD until you are aiming at the touchdown spot! Then the scan is simply touchdown point - speed - touchdown point - speed. Small prompt throttle changes control speed fluctuations; don't worry about the cause, just keep zero optical spin rate on the touchdown point and control IAS with power!
BEagle is offline  
Old 15th May 2009, 07:13
  #14 (permalink)  
 
Join Date: Oct 2004
Location: UK
Posts: 6,582
Likes: 0
Received 5 Likes on 5 Posts
Beagle quotes the standard RAF method as taught by at least one well respected FTO teaching FIC. If the aircraft is at the correct height when full flap is taken there should be no problem and I suspect the SOP originates from the same stable.

My experience of PPL students who may not roll out on finals at the correct height, leaves me a little cautious and I have always adopted the technique of teaching selection of (land) flap when its safe to do so.
Power controls rate of descent, pitch controls airspeed
It can do, but its much more efficient to hold the required attitude with pitch and maintain speed with the throttle! Holding one of two variables constant, only leaves you with one variable to correct for. The RAF required us to teach this method on Flying Scholarships.
Whopity is offline  
Old 15th May 2009, 07:20
  #15 (permalink)  
 
Join Date: Feb 2007
Location: Woking, Surrey
Age: 43
Posts: 159
Likes: 0
Received 0 Likes on 0 Posts
But why should we be teaching civilian pilots the same way as military ones? I agree that the mil have some great ways of teaching and produce the best pilots, but they do hand pick the people with the most ability to start with. The military world is also gearing the students up to become pilots of high performance aircraft, so teaching the techniques used in those aircraft from the onset is probably a consideration.

I don't think that earlier solo really matters in the civil world, we need to get civilian students to be able to control the aeroplane before they go solo. Probably the reason for teaching elevator for speed and power for rate of descent is to re-enforce in the student's mind that if you apply back pressure your speed will reduce whatever the power setting, and that if you make a power setting change you need to adjust pitch attitude. As the pilot becomes more experienced (post-PPL), sure they can adjust their own technique to one that is more "energy management".

I'm willing to be educated (having only just gained my FI(R)), but I think this is the kind of thing that we discussed on my course.
JonathanB is offline  
Old 15th May 2009, 07:25
  #16 (permalink)  
 
Join Date: Oct 2004
Location: UK
Posts: 6,582
Likes: 0
Received 5 Likes on 5 Posts
But why should we be teaching civilian pilots the same way as military ones?
Guess where the PPL syllabus came from! The RAF, by courtesy of Ron Campbell, the same syllabus the JAA adopted. The basics are the same and sometimes you can learn from the experience of those who have done it the longest.
Whopity is offline  
Old 15th May 2009, 07:31
  #17 (permalink)  
 
Join Date: Nov 2007
Location: Yellow Brick Road
Posts: 1,127
Likes: 0
Received 0 Likes on 0 Posts
I think the main point about full flaps is that these are drag flaps rather than lift flaps. Consequently you do not select full flaps until you are certain of reaching the runway, and you can only judge this on final. Once full flaps are extended, you are committed to land. The same principle applies to both powered and glide approaches.

The point at which you select full flaps does not have to bear a relationship to the height AGL of the aircraft. Nor does it affect a go-around because you will be retracting flaps for that anyway (subject to what your POH says). Twins are different but I presume we are discussing singles here.
ReverseFlight is offline  
Old 15th May 2009, 07:34
  #18 (permalink)  
 
Join Date: Apr 2009
Location: Lancashire
Age: 39
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
Hi all,

Just thought I'd add to this. My FI teaches the point & power. To be honest, I haven't come across anyone that teaches the Pitch = Speed & Thrust = Altitude/Rate of descent.

As I fly from an international airport, I'm always told not to lower the drag flap (30 in my 152) until we receive clearance from ATC to land. Typically around 300-400ft and about 0.5nm from threshold.

Makes sense to me to follow this where I am as the main rwy is used for commercial traffic to backtrack/position etc.. so the possibility of a late go around is present. Suppose its better to only have 20 flap if we get a late go around rather than struggle to get +rate with 30.

It can be a bit of slow ride down if your trailing 30 all the way down finals!! - Gotta love the logic of some people!


AWNT
AreWeNearlyThere is offline  
Old 15th May 2009, 07:37
  #19 (permalink)  
 
Join Date: Jul 2003
Location: these mist covered mountains are a home now for me.
Posts: 1,785
Received 29 Likes on 12 Posts
Why is everyone mentioning "being certain of making the runway"?

When the reduction of just a few RPM of power is enough to land short, in most/all aircraft an engine failure is extremely likely to guarantee it!

I also argue the point that full flaps means you are committed to land. Going round is always an option - even after the flare/bounce/wibble.

As for the throttle/IAS/Aimpont debate, I've done it both ways, and the Air Force method is simply easier. However, if your own technique works, and you are happy with it, then fine. It can't hurt to have someone show you another method sometime though.
Runaway Gun is offline  
Old 15th May 2009, 07:41
  #20 (permalink)  
 
Join Date: Mar 2009
Location: Perth
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
I guess all points are fair enough, but to prevent thread drift by debating the speed/power control philosophy, I think the point about when to take drag flap (which I take to mean 40 deg) is the topic, and I could be convinced either way by a compelling argument about taking either:
  • 40 deg flap as early on final as practical and trimming, then focusing on the airspeed/attitude all the way down, or,
  • 40 deg flap at mid-final (say 300' AGL) when I was taught to do PUFF (Pitch (Carb Heat off in 152), Undercarriage, Flap, Fixtures) checks.
I think the point is that in a training aircraft, it is reasonably forgiving so that either method is safe and easily learnt. Just from an airmanship perspective when there's a KingAir on long final coming up behind a crawling 152 a bit quickly is when I would be saying let's get down to the runway as 'efficiently as possible' so the KingAir doesn't have to go around.
smudgiebottom is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.