2017.0720 FLYING LESSONS

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FLYING LESSONS for July 20, 2017

FLYING LESSONS uses recent mishap reports to consider what might have contributed to accidents, so you can make better decisions if you face similar circumstances. In almost all cases design characteristics of a specific airplane have little direct bearing on the possible causes of aircraft accidents—but knowing how your airplane’s systems respond can make the difference as a scenario unfolds. So apply these FLYING LESSONS to the specific airplane you fly. Verify all technical information before applying it to your aircraft or operation, with manufacturers’ data and recommendations taking precedence. You are pilot in command, and are ultimately responsible for the decisions you make.

FLYING LESSONS is an independent product of MASTERY FLIGHT TRAINING, INC. www.mastery-flight-training.com

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This week’s LESSONS: A light jet overran the runway at Chicago Midway Airport. Perhaps because the new jet model was the first of its type delivered to a customer, images of the aftermath received widespread distribution in aviation-oriented media. “Preliminary information from video footage and ADS-B data suggest that the aircraft landed on runway 31C and steered off the left side of the runway just prior to reaching the Engineered Material Arrestor System (EMAS) pad at the end of the runway,” according to a report. See https://aviation-safety.net/wikibase/wiki.php?id=196631

Light rain was reported at the time of the overrun, and the pavement in the photo appears quite wet. Witnesses state it had rained heavily before the HondaJet, arriving from Philadelphia, attempted landing on the 5141 x 150 foot (1567 x 45.7 meter) Runway 31C.

The FAA’s Airplane Flying Handbook tells us:

! Dynamic hydroplaning occurs when there is a film of water on the runway that is at least one-tenth inch deep. As the speed of the airplane and the depth of the water increases, the water layer builds up an increasing resistance to displacement, resulting in the formation of a wedge of water beneath the tire. At some speed, termed the hydroplaning speed (VP), the water pressure equals the weight of the airplane and the tire is lifted off the runway surface. In this condition, the tires no longer contribute to directional control and braking action is nil.

! Dynamic hydroplaning is related to tire inflation pressure. Data obtained during hydroplaning tests have shown the minimum dynamic hydroplaning speed (VP) of a tire to be 8.6 times the square root of the tire pressure in pounds per square inch (PSI). For an airplane with a main tire pressure of 24 pounds, the calculated hydroplaning speed would be approximately 42 knots.

! It is important to note that the calculated speed referred to above is for the start of dynamic hydroplaning. Once hydroplaning has started, it may persist to a significantly slower speed depending on the type being experienced.

! Reverted rubber (steam) hydroplaning occurs during heavy braking that results in a prolonged locked-wheel skid. Only a thin film of water on the runway is


required to facilitate this type of hydroplaning. The tire skidding generates enough heat to cause the rubber in contact with the runway to revert to its original uncured state. The reverted rubber acts as a seal between the tire and the runway, and delays water exit from the tire footprint area. The water heats and is converted to steam which supports the tire off the runway.

! Reverted rubber hydroplaning frequently follows an encounter with dynamic hydroplaning, during which time the pilot may have the brakes locked in an attempt to slow the airplane. Eventually the airplane slows enough to where the tires make contact with the runway surface and the airplane begins to skid.

! The remedy for this type of hydroplane is to release the brakes and allow the wheels to spin up, then apply moderate braking. Reverted rubber hydroplaning is insidious in that the pilot may not know when it begins, and it can persist to very slow groundspeeds (20 knots or less).

! Viscous hydroplaning is due to the viscous properties of water. A thin film of fluid no more than one thousandth of an inch in depth is all that is needed. The tire cannot penetrate the fluid and the tire rolls on top of the film. This can occur at a much lower speed than dynamic hydroplane, but requires a smooth or smooth acting surface such as asphalt or a touchdown area coated with the accumulated rubber of past landings. Such a surface can have the same friction coefficient as wet ice.

! When confronted with the possibility of hydroplaning, it is best to land on a grooved runway (if available). Touchdown speed should be as slow as possible consistent with safety. After the nosewheel [or tailwheel—tt] is lowered to the runway, apply moderate braking. If deceleration is not detected and hydroplaning is suspected, the nose should be raised [in tricycle-gear airplanes] and aerodynamic drag utilized to decelerate to a point where the brakes do become effective.

! Apply brakes firmly until reaching a point just short of a skid. At the first sign of a skid, release brake pressure and allow the wheels to spin up. Maintain directional control as possible with the rudder.

! In a crosswind, if hydroplaning should occur, the crosswind will cause the airplane to simultaneously weathervane into the wind as well as slide downwind.

See www.faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-4of7.pdf

Note the main wheel tire pressure for the airplane you’re flying, and compare that pressure to the actual touchdown speed (which should be very close to the stalling speed as adjusted for airplane weight). You may find that your normal landing puts you close to a hydroplaning speed. For example, the Beech A36 Bonanzas I usually fly have a nominal main gear tire pressure of 33 to 40 psi. At light weights, such as at the end of a trip, the computed hydroplaning speed is 52 knots.

I used to fly a Baron 58TC. Nominal main gear tire pressure in those airplanes is 76 to 82 psi. Published landing speed at maximum gross weight is 78 knots, and although not published in the POH would be only slightly slower than that at realistic lower landing weights. There is extremely little margin between the essentially short-field landing touchdown speed and the NASA hydroplaning speed—you need to be very careful and land much slower than many pilots routinely land to avoid hydroplaning on a wet runway in an airplane like that!


Note these would be groundspeeds, the speed the airplane’s tires would be traveling across the wet surface. This becomes important as we return to the case of the Midway HondaJet.

METARs around 1836Z, the time of the mishap, are listed below. I’ve highlighted some important information.

KMDW 121853Z 18009G17KT 10SM -RA FEW060 BKN110 BKN130 OVC200 23/21 A2991 RMK AO2 LTG DSNT NE SLP120 P0007 T02280211 $

KMDW 121753Z 21011KT 10SM -RA FEW040 SCT090 BKN120 OVC200 23/21 A2996 RMK AO2 LTG DSNT ALQDS RAB37 SLP135 P0001 60060 T02280206 10256 20206 51006 $

KMDW 121653Z 20011KT 10SM FEW045 SCT060 BKN110 OVC150 23/21 A2995 RMK AO2 LTG DSNT W AND NW RAE41 TSE09 SLP133 P0001 T02280211

The HondaJet, landing on Midway’s Runway 31C, touched down with a variable and at times gusty wind…100° to as much as 130° off the runway heading, a crosswind-to-tailwind landing.

I have not been able to find data on the HondaJet’s tire pressure or typical touchdown speed in online aircraft specifications. Perhaps a FLYING LESSONS reader can let us know if the combination of the two puts the aircraft at risk of hydroplaning when landing with a slight tailwind. The trend established by the NASA Tire Pressure vs. Hydroplaning Speed table, however, suggests this to be a potential hazard. See http://www.hondajet.com/hondajet/Specifications

To minimize the hazard of hydroplaning when landing on a wet runway:

• Fly the proper touchdown speed—as slowly as possible to just above the stall speed at the moment of touchdown to preserve a hydroplaning speed margin.

• Land aligned with the runway centerline with zero slideslip, using appropriate crosswind control inputs. This is a basic requirement for passing the Private, Recreational and even Light Sport Pilot checkride—so it should be your routine for all landings, and all your landings become good practice for landing on a wet runway.

• Touch down as close to the approach end of the runway as possible, to maximize available landing distance.

• Plan a “firm” but smooth arrival, to put the tires solidly against the pavement. Don’t try to “grease it on” if the runway is wet.

• Lower the nose or tail wheel as soon as possible to maximize steering capability. But don’t push the wheel down and cause the airplane to wheelbarrow, or induce a pilot-induced oscillation.

• Avoid applying brakes at or above the NASA critical speed for your airplane. Land at a speed and with remaining runway distance that permits coming to a stop with little or no braking. Once below hydroplaning speed for your airplane, brake firmly without causing the tires to skid. Treat a wet runway like you’d treat one with a film of ice.

• Execute an immediate go-around if you detect hydroplaning upon touchdown, unless you have a runway much longer than your computed landing distance with a very healthy margin.

• Divert to a more suitable airport if a wet runway is combined with a significant crosswind or tailwind component. You might hydroplane off the side or end of the runway.

Some pilots advocate retracting flaps to put more weight on the wheels, increasing braking and directional control. Attempting to retract flaps during the landing roll is a common cause of inadvertent landing gear retraction in retractable gear airplanes, however, so I recommend against this practice in retractable gear airplanes. Comments? Questions? Let us learn from you, at [email protected]


See www.pilotworkshop.com/blog/lost-comm?ad-tracking=lost-comm-turn

Debrief: Readers write about recent FLYING LESSONS:

Reader Steve Guetter writes about last week’s LESSON: Twins and the Impossible Turn:

Excellent Article Tom! I passed it on to one of my Baron clients. Retired A320 Captain. He bought the Baron and I did his initial VFR checkout. A few months passed, he was working to get used to the plane then he came back for an IPC. The first time we were going to take off he begin to pull on to the runway without a pre-takeoff brief. I of course had him stop and we went through the brief together.

What struck me is how quickly some of the things we teach start to fall out of practice!

Indeed, Steve. That’s why we have refresher training. See http://www.mastery-flight-training.com/20170713-flying-lessons.pdf

Reader Don Peven asks about a recent LESSON on autopilot and trim malfunctions:

In the case of a severe autopilot malfunction like you relate in this week's MFT, if one was unable to get the autopilot to disconnect and couldn't manage to pull the circuit breaker, would it make sense to turn off the master switch? I presume that would turn the autopilot off, although you would also lose electrical instruments, GPS, and radio. Especially in VFR conditions, if it was the best way to avoid a crash wouldn't turning off the master be the most reliable way to kill the autopilot?

That’s another option, certainly. If unable to remove electrical power using the “usual” emergency procedure, removing power in any way possible is preferably to doing nothing at all. As you say, you would have a host of other outages and abnormal operating conditions as a result. Practice the emergency procedure, but—as you did—be creative if you have to in the event of an abnormal or emergency condition. Thanks, Don.

Reader Steve Freedman is thinking about the same LESSON:

Hi Tom, I just read your article regarding the flight control checks and AP [autopilot] checks. Thank you for the KFC200 check…it is very similar to the one I made based on the Pilot Guide and the POH Supplement, but I like yours better so I hope you don’t mind if it works its way into [my airplane].

One of the first things I did in my V35B Bonanza with the KFC200 autopilot is to have the Trim Circuit Breaker and the AP C/B capped with bight red caps/collars to make it easy to pull them in the event of an emergency. The best $1 you can spend in aviation…well that is because everything else is more than $1. I recommend all AP and trim C/B be capped so they can easily be found. Just like what you have written here. I think that story or the story of the AP LOC and fatality made me install the collars.

I just did a stuck trim stab scenario in the Boeing 757 today and it was a handful to fly out of trim.

I had my annual performed recently and the trim was set up poorly and I noticed right at rotation…a bad time to notice it. Not a big deal because I’m used to flying out of trim in the T-6 when I was an instructor we took the aircraft from the students and it wasn’t in trim when they started training. That’s almost what it felt like when I rotated. We got it fixed but it was not an optimal situation.

Training and pre planning occasional pay off. Hopefully I never need to cash that big check…I just wish the training and planning in the bank earned interest. Maybe it does…


Thanks, Steve. You don’t need to know something until you need to know it. That’s why we have training and practice. See https://www.faasafety.gov/files/gslac/library/documents/2011/May/54237/FLYING%20LESSONS%20110519.pdf Comments? Questions? Let us learn from you, at [email protected].

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See you at Oshkosh! I hope to see you at EAA AirVenture 2017. If you get a chance, please attend my program:

Stop Talking About Safety Everyone thinks he/she is a “safe” pilot. But the mishap record shows not everyone avoids accidents. Safety is an outcome, not a strategy, the result attaining mastery and command of their aircraft. Here are some easy techniques you can use.

I’ll be speaking the FAA Safety Center (near the base of the control tower) on Friday, July 28 at 2:30 pm.

I’m also presenting a version oriented at flight instructors in the NAFI (National Association of Flight Instructors) Professional Development Center on Monday, July 24 at 1:00 pm. Here’s more information about my program and the NAFI PDP seminar series.

I’m also in the American Bonanza Society tent most of the week (although I have several meetings during AirVenture), and on the ABS/Beechcraft Pilot Proficiency Program panel for “Flying Beech Airplanes” Thursday at 10 am in EAA Forum Pavilion #2.

I’ll see you at Oshkosh! See: https://www.eventbrite.com/e/stop-talking-about-safety-by-tom-turner-registration-36338014981 https://www.nafinet.org/PDCSchedule.aspx www.bonanza.org

Share safer skies. Forward FLYING LESSONS to a friend

Pursue Mastery of Flight.

Thomas P. Turner, M.S. Aviation Safety Flight Instructor Hall of Fame 2015 Inductee 2010 National FAA Safety Team Representative of the Year 2008 FAA Central Region CFI of the Year Three-time Master CFI

FLYING LESSONS is ©2017 Mastery Flight Training, Inc. For more information see www.mastery-flight-training.com, or contact [email protected].

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2017.0720 FLYING LESSONS