Getting tired of reading about Cirrus landing accidents? We've seen a lot of them. Let's do something about them. But first, why so many?
A common factor emerges: landing with excessive speed.
But then how should you land a Cirrus? And how do you land your Cirrus? If you do it differently, then what are the risks?
To find out, I spent some time reviewing recent COPA forum threads, such as Airspeeds -
Landing Poll SR22 Only and Another, ho-hum,
landing incident/prop strike and the recent accident thread SR-22 landing
mishap in Mulege, Baja Sur.
And those threads convinced me of two things: 1) people are using the same words to describe different things, and 2) I needed to see this for myself.
So, at the recent Cirrus Pilot Proficiency Program at Evansville, IN, I took my camera out on the ramp and photographed two CPPP instructors while they flew Cirrus SR22 and landed them in front of me. The first helped me with my photographic technique, but my camera failed me and the picture were out of focus. The second attempt was perfect.
Here's a sequence of photos of the landing, taken from south to north on runway 36 at KEVV. (Click to see a larger view, or see the full-sized photographs below.)
Very pretty airplane, very pretty landing. (FYI, this is N430CD, a Worpe9 variant of the SR22 from Next Generation Aircraft with a refit TAT Turbo engine, Avidyne Release 9 avionics, updated interior and new paint scheme; but of course, that had nothing to do with the landing, eh?) We'll use the paint scheme to highlight the attitude as the plane progresses through the landing sequence.
Factors in Cirrus Landing Accidents
But back to the landing accidents in a Cirrus. At least 30 aircraft have had substantial damage due to landing accidents, at least two of them fatal: Gurupi, Brazil when the wing tip touched the ground and the plane cartwheeled killing the pilot, and Crystal, MN when landing in rain and the plane failed to execute a go around after touching down. These accidents involve many variations of problems, such as loss of directional control after touchdown, pilot induced oscillations, and running off the end of the runway.
A common factor, not necessarily the cause but something that stands out, emerges: excessive landing speed.
What the POH says about Normal Landings
Here's what the POH states (see page 4-18 in the section on Normal Procedures):
Normal landing approaches can be made with power on or off with
any flap setting desired. Surface winds and air turbulence are usually
the primary factors in determining the most comfortable approach
Actual touchdown should be made with power off and on the main
wheels first to reduce the landing speed and subsequent need for
braking. Gently lower the nose wheel to the runway after airplane
speed has diminished. This is especially important for rough or soft
Seems simple enough, eh? Approach can be in any configuration. Conditions may determine speeds. Touchdown on the main wheels first. Lower the nose wheel after speed has diminished.
Unfortunately, training was overtaken by events. Tail strikes happened frequently enough in new airplanes during transition training that instructors began adding more speed to keep the plane from dropping onto the runway. A bit of a good thing gone bad!
What does the Flight Operations Manual say about Normal Landings
Another guiding document from Cirrus Aircraft gives instructors and pilots standardized procedures. Here's the section on Normal Landings (see page 3-66 in the section on Standard Operating Procedures):
Normal landings should be made with 100% flaps. Final approach
speeds should be adjusted to account for gusts exceeding 10 KTS by
adding half of the gust factor. Reduce power smoothly and begin
slowing from the final approach speed at a time that allows an easy
transition from final descent to round out and flare with minimum
floating or ballooning. Touch downs should be made on the main
wheels first at speeds slightly above stall. Gently lower the nose wheel
after the mains are on the ground.
More rigorous than the POH and more descriptive of the technique. Introduces the distinctions of final approach, round out, flare and touch down. However, this remains consistent with POH.
A great diagram is also provided to show the airspeeds and configurations in the traffic pattern:
What do we mean by "landing speeds"?
So, if the guidance is consistent and standard, why do we have a problem? Seems that people use the phrase "landing speed" to refer to different phases of the normal landing procedure. Here's my take on the distinctions:
- final approach speed: the airspeed with 100% flaps during the descent towards the runway
- short final speed: the airspeed for the last part of the final approach, often less than a mile down to about a quarter mile
- over the fence speed: a colloquial term without precision, because where is the fence in relation to the runway threshold
- over the numbers speed: another colloquial term that at least refers to the landing portion of the runway beyond the threshold
- Vref speed: airspeed for crossing the landing threshold of the runway, defined as 1.3 times Vso, the stall speed in landing configuration at most unfavorable weight & balance
- round out: the transition from nose-down attitude during final approach to nose slightly high to enter ground effect over the runway
- flare: the nose slightly high attitude as airspeed decreases in ground effect prior to touch down
- touch down speed: slightly above Vso, the full stall speed
What does it look like to land this way?
Frankly, that's a lot of words. So, what does it look like when a plane is landed according to the Flight Operations Manual and the POH? Here's the overview and then we can review each photograph.
Short final, about 1/4 mile from the runway threshold, 80 KIAS, 100% flaps, attitude slightly nose down (doesn't the paint scheme really help here?!)
Reducing power to slow from short final speed of 80 knots to Vref speed of 75 knots.
Vref at 75 knots over the threshold markings on the runway. (Runway 36 at KEVV has a displaced threshold and it is visible in the heat haze.) This airplane is a turbo with a composite prop, and the plane will decelerate quite rapidly as the power is pulled back, so expect the descent rate to increase. Note that the attitude is still slightly nose down.
Round out and flare brings the nose up slightly with smooth application of elevator pitch. Speed decreases as plane flies in ground effect.
Touch down on the main wheels at a speed just above Vso stall speed of 60 KIAS, with nose wheel still off the ground in a slightly nose up attitude. Note that this is not "flying it onto the runway" but rather holding it off the runway until speed decreases to let the plane settle down out of ground effect. The main wheels touch first and the plane continues to roll until the nose wheel drops.
Holding the nose wheel off the ground after touch down. Note the elevator position keeping the attitude slightly nose high. The pitch attitude does not require much angle of attack to maintain the nose wheel off the runway.
Nose wheel down. Note elevator position indicates some remaining pitch control.
Completed landing and application of brakes. Very pretty airplane, nicely landed.
Your landing check ride
We encourage you to fly with a safety pilot or an instructor to review what airspeeds you fly when landing. They can call out or write down the speeds on short final, across the threshold, as you round out and flare and touch down. They might also note the position on the runway where you round out and touch down.
What can go wrong?
This landing was typical of what the CPPP flight instructors seek as proficiency in Cirrus pilots. Unfortunately, not everyone comes with good landing habits. What can go wrong?
- float forever: if the speed over the threshold is too great, it may take a long, long, long time for the plane to slow down.
- nose wheel lands first: flying the plane onto the runway risks touching the nose wheel first, and that may cause a rebound into the air and starting a pilot induced oscillation
- planting the main gear onto the runway: forcing the plane to touch down before it has stopped flying means it may start flying again before you are slowed down enough; why? a gust of wind may provide lift, or a bump in the runway surface may provide upward thrust, or the main gear spring into action and provide upward thrust on their own
- brake lockup: with a free castering nose wheel, you may have directional control problems if the brakes lock up unevenly
Proficiency in landing will reduce risk of accidents
Become proficient yourself. Watch for other Cirrus pilots who carry excessive speed in their landings. Tactfully intercede. Help them become proficient and avoid an accident.
7 Jun 2010 21:12