stall warning and when to panic
 

I often fly with a much more experienced pilot. Conducting night circuits for recency requirements, I was a little perplexed turning onto final from base with a little wind behind us that my more experienced friend was banking greater than 30 degrees while the stall warning alarm was going off at 500 feet, yet didn't do anything to correct i.e. increase speed or reduce bank angle. My friend does have a a slight hearing problem so I assumed he was not hearing the stall warning. We did a touch and go but on crosswind he said he was happy with the speed turning final. I have only 250 hrs and I have a spinning endorsement but my friend has over 2000hrs and I was a little freaked out that he wasn't concerned about the stall warning alarm going off at 500 feet. Am I just too pedantic? I would really like advice form those with more experience.

When you say 'going off' do you mean blaring, or 'peeping' with gusts? Some aircraft (mine included) have the stall vane set pretty conservatively, and are also more prone to peeping than e.g. typical SE Cessnas. That said, I would be concerned about too-steep turns in the circuit at night.

I'm only a 200 odd hour guy myself but if I heard the stall warner turning finals I think I would have been in 'I have control' mode, regardless of the experience of the handling pilot. It's your neck on the line as well.

I learned in Tomahawks (good spinners) and the one thing I remember being drilled home more than anything was 15 degree angle of bank on turn to finals, no more than a single stage of flap and AIRSPEED! 70 knots, add 5 if you feel unsure/uncomfortable/weather conditions dictate it! I never forgot this ...

I am currently "refreshing" ], and the only thing to add to this (apart from the Cessna 152 is 65 knots and you can use 2 stages of flap as there are 3 on the Cessna's), is don't start the final turn below 800ft QFE.

I'm no expert, but these are all lessons I don't think will every leave me due to the fact they have been shouted at me so many times!!!! :O

You were taught a load of rubbish then teknow. And the 800ft is a load of rubbish as well unless its some noise rubbish.

As for the stall warner going off and not doing anything its bad form especially at night. A chirp or two is acceptable but continuious is silly.

The finer point that's often not fully learnt is that when you roll into a descending turn you need to adopt a slightly lower nose attitude to maintain the (correct) speed.

mad_jock, I concur with your comments!

I'm a low hours PPL, so would appreciate an explanation to that!

I understand why the "taught" methods may be rubbished by a more experienced pilot - my understanding is these methods/guidelines are put in place to deter the student pilot being too "gung-ho" and doing something dangerous?!

Getting a little off-topic I guess but as an inexperienced pilot the moment I heard that stall warning, I'd be lowering the nose, reducing the angle of bank and applying power.

Are you sure you have 250 hours?

Agree with points made above. A little chirp or two, especially if its a bit windy I would be okay with. If it was going off continuously I would be telling my friend (hopefully before the speed got THAT low) to check the speed and if he didn't remedy it I would take control.

teknow, I don't agree with those things that have been drilled into you, but I have never flown a Tomahawk. In general though, fly a proper speed, don't bank stupid amounts, and don't let the turn slip or skid. Those are the main things I would be concerned with. More than 15 degrees of bank I don't see a problem with (unless you're too slow and/or uncoordinated) and do it at a height that is appropriate to how tight you are doing your circuit. Flaps again I don't know for the Tomahawk but I see no reason to restrict their use on a 152.

65kts for a 152? Bit fast I think. Tecnow it seems to me that you are flying at a 'add 5 kts for the wife and kids and then another 5 if there's an R in the month' type of place. Have a look at the POH (clues in the name...:)) for the correct speeds and techniques. Having said that if your club has a particular policy then you need to abide by it.

When the load factors go up, so does the stall speed. Most have an understanding of this.

But did you know that in a 45 degree turn the stall speed goes up with over 40%? That's quite a lot. So, if you're low, heavy, have marginal speed already and gusty winds, it is imperative that you increase your speed either with throttle or by pushing nose down when you turn. There is nothing dangerous with a steep turn down low as long as you protect your speed. Or even better, install a cheap AOA meter and take the guesswork out of it.

Teknow
 

I regret to say that you are the victim of poor instruction you flight should be arranged to arrive at the threshold at 1.3 Vs if I remember correctly the PA38 has a Vs (full flap) of 48 Kts so that should be 61.1 Kts.

65 Kts would be a reasonable speed to aim for on final with a reduction to 62 Kts ( I can't read the ASI to 0.1 of a KT) as you come over the hedge. If is was very gusty then 70kts is the maximum ( reducing to 64 Kts at the threshold) I would use in normal flying practice any more and you are going to float half way down the runway and risk all sorts of pilot induced oscillation problems near the ground.

Its just part and parcel of the lack of attitude flying thats being taught.

They should add 2 circuits with all the instruments covered into the ppl test, that would sort alot of this pish out.


Reckon that 800ft is some nosense to do with commercial stabilised approach gate at 500ft. Its guff what ever the reason.


BTW the tommy is quite happy at 55knts approach speed full flap for a short field landing.

With 15 knts on the nose and 2 up and 2 hours in the tank you can stop in the space of the piano keys.

Adam Fritch said "But did you know that in a 45 degree turn the stall speed goes up with over 40%?"

Errr No! The stall speed will incease by a a factor of 1.19 at 45%. This would be logical as a glider with a stall speed of 40knts is often thermalled at 50 knts and 45 degrees. Source wikipedia

Stall speed increase=square root of load factor. Therefore I put my money on Cumulus Rider.

Adam: At least you are erring on the right side of safety!

Well with my base you'd be limited to a straight-in approach. (Circuit height 800'). At a neighbouring airfield the circuit height is 500' QFE. So, for you that would be another straight-in as you couldn't possibly turn final at 250'.
Could you?

Mad Jock is quite right regarding the Tommy and 55kts.:ok:

AdamFrisch, nothing?

A and C, am with you but on a point of technicality our Flight Manual states 63 kts for scheduled performance etc.

For the record the load factor varies as the secant (ie 1/cosine) of the bank angle. Secant 45 degrees = 1.4 as near as dammit.

Stall speed increases by square root of the load factor - square root of 1.4 is circa 1.19 - there stall speed in 45 degree bank (level) turn increases by near enough 20%.

I knew there was a reason for all the trigonometry at school!

mad_jock, with you all the way about attitude flying etc.

Firefly:

Unless I'm misreading what you are putting the load factor increases as the secant of the angle, not the stall speed. The stall speed is the square root of the load factor.

IE the load factor in a level 60 degree turn is 1/cos60 which is 2. So you are pulling 2g in a level 60 degree turn. The stall speed will increase by the square root of 2 which is 1.414. So if stall speed in level flight is 50kts, youre stall speed in a level 60 banked turn is 70kts.

The amount of chuff I've heard over the years from people who have no clue about the relationship between angle of bank and stall speed is astounding!

You can roll an aircraft to any flipping angle of bank you want without an increase in stalling speed as long as you don't load it up with G. People seem to lose sight of the fact that examples given to demonstrate the increase in stalling speed for a given angle of bank are only related to maintaining level flight in a turn.

For my own aircraft I know off the top of my head the 1, 2, 3 and 4g stalling speeds as these are of far more use no matter what amount of pitch or roll I have on.

Getting back to the original question, I was flying a G1000 C182 a fair bit until recently and the stall warner on that would go off so far above the actual stall that it was more of an annoyance than a benefit for a short field approach!

Regards

UA

Er...thought that's what we were talking about...I agree with your other stuff by the way.