C172/Full Flaps/Ac veered off runway

[extricate]

Hi,

Apologies that this is a GA question. I've read a report about a student pilot who forgot to flaps up after touch n go, and the aircraft veered off the runway even after kicking in right rudder. I'm trying to understand why it happened and would like more advice on this.

With full flaps, could it be that even with full power, due to the disruption of airflow around the aircraft (slipstream effect), the flaps rendered the rudder ineffective in directional control and as a result, the aircraft could not get back on track?

Many thanks

[9 lives]

With full flaps, could it be that even with full power, due to the disruption of airflow around the aircraft (slipstream effect), the flaps rendered the rudder ineffective in directional control and as a result, the aircraft could not get back on track?

In a word, no. With full flaps and adequate flying speed, the rudder of a 172, and any other certified 'plane, is effective to maintain directional control.

If the pilot did not maintain adequate flying speed, and the aircraft was airborne, application of rudder might not have been adequate to maintain directional control, particularly if the pilot was attempting to maintain wings level close to the ground. That's spin territory.

Any 172, and indeed any certified airplane, will climb away adequate with full flaps and full power, it's a "balked landing" climb requirement for certification. But, like any flying, it presupposes that the flying speed is adequate, and the flight is coordinated.

A 172 is not a terribly "torquy" aircraft (compared to a 185/206/210). Some right pedal may be required during full power on the ground to keep it straight, but not a large amount. I have flown 206's where, with a bit of adverse crosswind, momentary full right pedal was required to keep it straight on the runway with full power. I have noticed that some pilots think that they have applied full pedal, but when I push on the pedal from right seat, there's more available. Cessnas have adequate rudder effectiveness.

Slipstream will not be a disruption of airflow, but rather a dis-symmetry of airflow, causing yaw. Some aircraft actually have a slight offset of the fin, to reduce pilot workload for this factor.

Full flaps on a Cessna will result in separated air off the flaps - disrupted airflow, but not enough to render the rudder ineffective. Rudders on some Cessnas (though no the 172) can be stalled. If you look at the difference in the dorsal fin of the earlier C 180, and the 185 (the latest 180's had the same dorsal fin as the 185), you will see Cessna's aerodynamic fix for a rudder which could be stalled - the changed dorsal fin prevents stall of the whole fin. I know this having flown modified 300HP C 180's, whose dorsal fin was not changed to be higher, and the rudder could be stalled, and would "lock", albeit gently.

So, unfortunately, sometimes a new pilot simply ends up off the runway for lack of piloting skill. Analyzing causes can be interesting, but you can be assured, that after 60 years, the 172 series is ultimately well known, with no skeletons in it's closet!

Apologies that this is a GA question

You don't have to apologize for asking questions.... That's what we're here for!

[extricate]

In a word, no. With full flaps and adequate flying speed, the rudder of a 172, and any other certified 'plane, is effective to maintain directional control.

Thanks for the info! Appreciate your time.

What would you have done, let's say you encounter this situation of aircraft veering sharply off the runway?

Situation: While rounding out, you kick in a little left rudder to track centerline and after touching down,you immediately apply full power but forgot to raise flaps up fully and the aircraft suddenly veered left sharply.

[27/09]

Situation: While rounding out, you kick in a little left rudder to track centerline and after touching down,you immediately apply full power but forgot to raise flaps up fully and the aircraft suddenly veered left sharply.

A C172 will not normally veer left sharply in the situation you describe.

What caused it to veer? Crosswind? Pilot induced? Either way use the rudder to prevent the yaw.

One comment I will make, is that far too often pilots do not watch what the aircraft's nose is doing relative to the horizon. They only react when the whole aircraft is veering left or right. By watching what the nose is doing, the correct rudder input can be made immediately before the aircraft has started to move off line.

Thinking about your post some more. You said "kick in a little left rudder to track the centreline". This infers there is a crosswind. Was the aileron correctly applied? Was the veering actually the aircraft rolling left caused by incorrect application of aileron?

[foxmoth]

Situation: While rounding out, you kick in a little left rudder to track centerline and after touching down,you immediately apply full power but forgot to raise flaps up fully and the aircraft suddenly veered left sharply.

What you often find is that an inexperienced pilot will take longer to detect the swing and longer to react, a more experienced pilot will not have allowed the swing to develop in the first place!

[BEagle]

Any pilot who 'kicks in rudder' should themselves be given a kicking!

There is never any need for sudden and violent rudder movements.

[Cows getting bigger]

I've seen this happen. Pilots need to understand that the throttle is not an on/off switch and any use need to be balanced with other controls (predominately rudder on the ground).

Shoreham have a really good webcam looking down the runway ( Webcam ? Brighton City Airport (Shoreham) ). Spend some time watching departures and notice how the vast majority fail to track the centreline on the ground and just after getting airborne. To me, this is indicative of a general malaise amongst instructors and a lack of understanding amongst pilots.

[9 lives]

notice how the vast majority fail to track the centreline on the ground and just after getting airborne. To me, this is indicative of a general malaise amongst instructors and a lack of understanding amongst pilots.

I agree with this, be sure that you're being fair to the 'plane first by flying it with precision. Although a 172 has ample control to recover, much better not to lose control in the first place. You have lost control if the 'plane is pointed a direction you did not intend to go.

Buy way of an extreme (and admittedly shameful to me) example of a 172's rudder control capability: I was asked to ferry a 172 from a small grass strip, to the maintenance airport. The 'plane had had some minor maintenance problem at the small grass strip (1600 feet by 20 feet wide), and a mechanic had been sent to repair. He had left the 'plane "repaired" to be flown home. I was going there anyway, so asked to fly it. Bright and early in the morning, no one around. Did my checks, fired it up, and taxied out. The surface was a mixture of turf and grass (some bare spots). I noticed that it did not taxi straight easily. I was maintaining my intended schedule, so planned to go. As I back tracked, still noticing the tendency to swing to the left while taxiing, I saw that the left wheel was not turning at all, just siding on the wet grass. Hmmm. Using a soft field technique from the wet grass, I easily became airborne. I knew that I could use the grass runway at the destination airport, rather than fouling up my schedule, and having the mechanic travel back to correct whatever error he had caused. I landed full flaps on the grass runway at the destination with no difficulty at all, and taxied up to the edge of the apron. I shut down there. The boss came out at asked me why I did not taxi up to the hangar. I smiled and said have your mechanic taxi it, he'll figure it out!

The 'plane had lots of rudder to overcome a locked wheel on wet grass.

I also agree that we do not kick, jab, or jam in control inputs, unless perhaps you're flying an aerobatic routine. The application of control should be smooth all the time. That does not mean slow, or lagging, but as the good pilot is "ahead" of the 'plane, they are not playing catch up, and having to suddenly apply control by surprise.

Depending upon your opportunity, I suggest that you fly the 172 for the purpose of practicing slips, with the intent of getting used to the application of full pedal - smoothly. At altitude, with appropriate set up, apply full pedal with compensating aileron, with and without power, get used to how much rudder is actually available. As I have said, I'm amazed sometimes when pilots seem to run out of rudder, I push a pedal, and lots more is available, that for whatever reason, they had not pushed.

[BackPacker]

Could it possibly be that the aircraft was held on the ground with full or almost full forward yoke well above Vr? In that case the aircraft may have been wheelbarrowing. Depending on the crosswind component, there may not have been sufficient rudder authority in that case (with the mains not touching the ground).

[TheOddOne]

I push a pedal, and lots more is available, that for whatever reason, they had not pushed.

Some of this is seat position. I always get students to spend some time sorting out seat position/leg geometry so that they will have full brake authority as well as full pedal travel. This usually means them sitting closer than they might in a car. I'm 6'2" with long legs and in both the PA28 and the C172, I need to move the seat forward to get adequate pedal authority. Of course, once having sorted out the legs, then comes eye position - the old '3 fingers on the coaming' routine. This needs to be absolutely consistent flight to flight. In airliners, it even matters about the relative position of the eye in all 3 axes. Older gate parking aids depended upon the left seat pilot eye being in an exact position relative to the rest of the aircraft for accurate parking.

I tell students (in a light-hearted vein) that the two hardest things to learn about flying an aircraft are
a) handling the a/c on the ground and
b) speaking on the radio.

TOO

[Shaggy Sheep Driver]

I remember back in the '70s when I first checked out in the delightful Chipmunk, the instructor said "when you can taxi this aeroplane accurately, you can probably fly it".

The Chippy's unusual steering, with a fully castoring tailwheel and differential main wheel braking operated by the rudder pedals, did take some getting used to.

The fly-off type hand brake lever has to be 'set' to any point between off (no braking even with full rudder applied) to fully on (both brakes on even with no rudder applied). Any point in between gives braking appropriate to how far back the brake lever is set, on the relevant wheel as the ruder pedals are operated. Once used to it, it is the best ground steering system I have come across in any aeroplane. It was very much in keeping with the Chippy's character, and the instructor was correct.

Going to Step's 'stuck wheel' episode reminds me of the Yak52. That has air-operated differential main wheel braking and a castoring nose wheel, the brakes (like the chippy) worked by the rudder pedals for appropriate wheel, but applied 'on' or 'off' by a bicycle-like lever on the stick. Trouble was, on wet muddy winter airfields applying brake to steer resulted in the appropriate wheel locking (the yak has quite narrow tyres) and the beast continuing strait ahead regardless of rudder position or brake lever operation.

I discovered the best way to make it turn in such conditions was by using bursts of power. The big Vendeneyef radial has massive torque, and a sudden application of power would dig the right hand main wheel into the mud, resulting in a right turn. Suddenly reducing power would dig in the left wheel, for a left turn! Worked well, if not good for the grass surface!

[Martin_123]

if it was a planned touch and go, my question would be - why are you doing it with full flaps out? The flight school I finished never allowed students to use full flaps on touch n gos for this particular reason - very easy to forget to bring them up.. 2/3rds or 30° depending on type was all you ever needed

the problem with older GA aircraft is that not all of them can actually meet certification standards 40 years since plane was built. I know of a recent incident where a fresh PPLer crashed a 152 in a very similar way, plane simply failed to climb, runway was running out, he lift up the nose and the wing dropped .. luckily he lived to tell the tale

then you have some clubs using MOGAS which with all the ethanol in it these days reduces the performance even further

I operate out of a rough grass field. We are pulling the nose back as soon as the throttle is advanced. You typically lift off before the plane is ready to fully fly - keep the nose level, build up speed and allow the plane to climb out of ground effect itself, assuming it's trimmed properly. Don't force the plane do things it doesn't want to do

[9 lives]

the problem with older GA aircraft is that not all of them can actually meet certification standards 40 years since plane was built.

Then the 'plane is not airworthy, don't fly it!

Otherwise, any certified 'plane whose condition is such that it meets it's certification standard (the TCDS and maintenance manual) will climb away safely with full flaps, if flown at the POH speed for doing that. I sincerely hope this is being trained and practiced (which may be done at altitude). Yes, with full flaps extended, if the pilot attempts to climb at too slow an airspeed, the plane will stall, as it always would.

then you have some clubs using MOGAS which with all the ethanol in it these days reduces the performance even further

Which is prohibited on every Cessna TCDS, unless specifically approved, and I have never heard of a Mogas approval which permitted ethanol, it is corrosive to some fuel system components. However, an aircraft which is properly set up to run on ethanol will perform as well as a gasoline powered 'plane, just burning more fuel. For a period, I flew a C 150 which was powered by 100% ethanol, and it was perfectly fine to fly, other than seeing a fuel flow of 13 - 14 GPH on takeoff, and smelling like a distillery. It would do everything a normal 150 would do, other than fly as far on a tank. We never STC'd that mod, as there were problems with documenting range and endurance for the POH supplement.

I operate out of a rough grass field. We are pulling the nose back as soon as the throttle is advanced. You typically lift off before the plane is ready to fully fly - keep the nose level, build up speed and allow the plane to climb out of ground effect itself,

Excellent! You'll have super flying skills, and never damage a nosewheel! This should be a normal skill for pilots flying GA tricycle aircraft.

[Pace]

I operate out of a rough grass field. We are pulling the nose back as soon as the throttle is advanced. You typically lift off before the plane is ready to fully fly - keep the nose level, build up speed and allow the plane to climb out of ground effect itself,

Just a caution it was believed the Jockey crash and fatality years back was caused by a Seneca becoming airborne too early.
On bumpy strips I have had the things airborne and flying at 60 KTS as a bump launches you airborne too soon with little control surface effectiveness if there is a power differential

Some singles too need caution flying too early

[Martin_123]

Then the 'plane is not airworthy, don't fly it!

eh if only if it was that simple... I can't say that I have much faith in the whole ARC/CofA system around GA.. It seems like the 'annual' is becoming more and more like an overpriced once-over with some engineers happy to sign-off just about anything with unsuspecting owner handing over large lumps of hard earned cash

as regards the fuel - when you have AVGAS at 2.30-3.00 yoyos per litre and mogas at 1.30, some people will just take that chance.. and seeing how one will get away, others will join in - that's the crowd mentality.. some people keep avgas in one tank, mogas in other and switch between them depending whether you're in a flight critical phase or cruise phase .. I haven't done it myself, but what I hear you loose about 100 rpms by using mogas on your typical continental o200

[TheOddOne]

never allowed students to use full flaps on touch n gos for this particular reason - very easy to forget to bring them up.. 2/3rds or 30° depending on type was all you ever needed

What???
We teach 40 deg of flap for every approach on our PA28, apart from practicing flapless and we aren't runway length limiting. It's what the POH says to do. Oh, and 63 kts final approach speed, too. We teach our students to retract the flaps as soon as all 3 wheels are on the ground - also as per the POH. We initially teach a 40 deg flap go-around as a part of the stalling exercises, then later on for real. My favourite scenario is to simulate entering the flare. As soon as the stall warner comes on 'look out, there's a fire truck on the runway!!'. Full power, correct the swing, climbing attitude, then drag flap away, note positive rate of climb, then retract other 2 stages.

BTW, on the PA28, we say 'extend' or 'retract' instead of 'raise' or 'lower', as the latter causes too much confusion with the position of the flap lever. Raise and lower is fine for the Cessna.

TOO

[9 lives]

I can't say that I have much faith in the whole ARC/CofA system around GA

Who cares about the system, it's the people you surround yourself with, which is important. If you don't have faith that the maintainers of the 'plane are keeping it airworthy, don't fly it, and don't associate with those people. As the pilot, it is you who are responsible for not flying a 'plane which you suspect may not be airworthy. The maintainers either satisfied you, or they did not, in any case, the decision to fly an airworthy 'plane lies with the pilot.

I hear you loose about 100 rpms by using mogas on your typical continental o200

If the Mogas is of an approved type (no ethanol), this is not correct. There will be zero affect on the operation of the engine. I have 3300 hours flying O-200's on Mogas, plus about 50 hours flying an O-200 on pure, or close to it ethanol. If you add more than about 5% ethanol to mogas, then yes, you may begin to see power reduction resulting from running lean. It won't be 100 RPM though, until the percentage of ethanol is much higher.

As soon as the stall warner comes on 'look out, there's a fire truck on the runway!!'. Full power, correct the swing, climbing attitude, then drag flap away, note positive rate of climb, then retract other 2 stages.

BTW, on the PA28, we say 'extend' or 'retract' instead of 'raise' or 'lower', as the latter causes too much confusion with the position of the flap lever. Raise and lower is fine for the Cessna.

Excellent, "extend" and "retract" are clear and concise. Now "stages", as I know it is for the theater. All the flaps I know in GA 'planes have extension expressed in degrees.

And thanks for "correct for swing", it means that we have not totally drifted this thread!

[Martin_123]

What???
We teach 40 deg of flap

I was talking about students being solo doing their circuit work.. of course instructors teach to use full flaps and that is expected from student later on in cross country phases and ultimately in exam.. but when you're still in circuit all alone doing touch and goes, then there's no need to go all the way

Who cares about the system, it's the people you surround yourself with, which is important. If you don't have faith that the maintainers of the 'plane are keeping it airworthy, don't fly it, and don't associate with those people. As the pilot, it is you who are responsible for not flying a 'plane which you suspect may not be airworthy. The maintainers either satisfied you, or they did not, in any case, the decision to fly an airworthy 'plane lies with the pilot.

this is probably one of the better advices I have read on this forum. It is very easy to get all intimidated when you're a fresh pilot owning your first plane trying to figure out what's what in this world.

[Cows getting bigger]

Hmmm, student T&Gs. I was taught to teach that a T&G was a landing followed by a take-off. Students tend to do rush things when close to the ground and there is scope for them to confuse the order of events. On one occasion I saw a student apply power and then retract flap to T/O; not good.

So, my thoughts as a chief flying instructor were that students should complete a landing in the correct landing configuration, reconfigure and then take off. If this couldn't be done safely, then the student was either not ready for solo circuits and/or the runway was not long enough for the solo exercise. As a rule of thumb, an average student in a PA28/C172 would need about 600m of runway to do this safely.

[ChickenHouse]

Apologies that this is a GA question. I've read a report about a student pilot who forgot to flaps up after touch n go, and the aircraft veered off the runway even after kicking in right rudder. I'm trying to understand why it happened and would like more advice on this.

I have seen similar only once in crosswind training, 172 with 40 flaps, student forgot to up the flaps and on pulling throttle was hit by a gust, result - unexpected added lift of the aircraft and he was simply blown off the runway, luckily on the wide gras runway aside, nothing harmed except the students pride.