Thursday, April 14, 2011

Crosswind to remember

The fourth day of a recent trip found me in Covington, Kentucky in a six-fifteen AM van, after sleeping fairly well for about the last seven hours. My cellphone playing U2 in the van alerted me to crew scheduling calling. What I dreaded wasn’t occurring; there was a plane at the airport with our name on it, but our revenue flight from Cincinnati to Philadelphia had been cancelled, and we were to ferry it there instead.

After researching the problem in the aircraft logbook, surveying the ferry flight permit, discussing it with my fine First Officer ‘Cindy’, performing all our checklists and briefings, and getting the frost de-iced from our wings, we sped down the runway in the morning light.

A single bell chime and flashing yellow ‘master caution’ light a few hundred feet AGL (above ground level) on climbout didn’t startle us, we expected it. The associated caution message on ‘ED1’, our display screen that shows our engine and fuel parameters, read in yellow letters “STEERING INOP”, referring to the nosewheel steering. At the appropriate time thereafter my F.O. read and performed the QRH (quick reference handbook) procedure for this message. Actually she read it and I performed it. This was simply to cycle the nosewheel steering switch (located on my side and accessible only to me) off and back on. The steering was restored, the message disappeared, and we continued upward and onward.

The previous crew flying this plane had received this message on climbout after retracting the gear, and during the approach to land after extending it. They ‘wrote it up’ after parking for the overnight in Cincinnati. This problem was why we were ferrying the empty jet to Philadelphia: you obviously don’t want passengers on a plane with its nosewheel steering on the blink.

During our talk on the ground in Cincinnati Cindy and I shared the hope that if the steering inop message occurred again with gear extension on the approach and landing into Philadelphia that we would be able to get it back via the same QRH procedure. A review of the weather in Philly gave us both some concern that a landing attempt without nosewheel steering would most likely be not advisable, or in plain words, unsafe.

A slow moving cold front and ‘associated low pressure system’ was finally finishing its path across the northeast, and the Philadelphia airport had pretty strong, gusty winds from the northwest at 29 to 37 mph. For our jet emptied of passengers, it would be a strong crosswind from the right side, relative to the west, landing on runway 27 (landing to the west, 270 degrees magnetic, wind from the northwest).

(This is a crosswind component chart.  See if you can determine the crosswind component for our conditions.  The runway direction was 270 degrees magnetic, the winds were blowing at 25 knots from a 330 degrees magnetic direction.)

This ferry permit placed in the maintenance logbook required that we land on runway 27L or 27R in Philly, the longest runways there; runways 26 (5000 feet) and 35 (6500 feet) were prohibited. In Cincinnati I thought about what I would do if we were unable to restore the nosewheel steering if it failed upon gear extension in these conditions upon arrival at Philadelphia. This was where someone would say that “this is why they pay you the big bucks”.

With no steering, I would’ve rather landed on runway 35, it was less of a crosswind than on 27 (20 degrees of crosswind instead of 60), but the ferry permit prohibited it. I could’ve called our Flight Department manager who authorized the permit and asked him to authorize 35, but that promised perhaps thirty minutes of work added to a morning which was already behind schedule, with no guarantee of success. We had been given a Baltimore alternate from our Dispatcher, which I appreciated, and that airport, with runways aligned to the northwest and more directly into the wind, would’ve been a better choice if we had to land without nosewheel steering.

The risk of losing the steering completely on approach was clear in my mind and gut as I decided to go ahead with the flight. I was confident that if it failed on gear extension that we would be able to restore it, because cycling the switch had worked in the past. My guess was that a nosewheel steering wire was getting pinched somewhere during the retraction and extension cycle, causing the steering to go offline. Because of this tendency, I felt fairly assured that it wouldn’t fail suddenly on landing after touchdown. But there are no guarantees in life, or in flight.

Landing without steering in a crosswind that strong would highly risk that differential braking (we brake the left and right main wheels separately) and aerodynamic forces from the rudder would not provide enough control to prevent the airplane from ‘weathervaning’ into the wind and then skittering downwind across the runway, and I didn’t want to try. In a normal crosswind landing, considerable steering input to the nosewheel is required during deceleration from landing speed to taxi speed (140 mph to 10 mph). With no steering, the nosewheels caster freely, much like a front shopping cart wheel.

I had landed without nosewheel steering before, as a non-flying first officer at Chicago O’Hare. The Captain did a fine job, we were towed in from the runway we closed down, and it’s a great story for another time. But that was in calm winds, not in a crosswind which had gusts exceeding the steady state crosswind maximum published for our jet.

We had over an hour airborne to think more about the possibilities that could happen. I decided and briefed that we wouldn’t attempt a landing without nosewheel steering at Philadelphia, that we would extend the landing gear ten miles out so we would have time to deal with a steering failure, and if the steering failed after touchdown I would apply maximum braking on the runway. It all sounded good to Cindy as well.

Once we reached the Philadelphia area, things happened fast, since we were arriving in between ‘pushes’, a busy time of arrivals, then departure. ATC vectored us quickly, and I thought that I should’ve managed my speed better as we noticed on a tight base vector that we were going to overshoot the final approach to runway 27R, due to a strong tailwind. I’m modest: the controller should’ve given us an earlier turn to final to prevent this from occurring in the first place. I hand flew a healthy crab angle back to the north, and we were basically aligned with the runway.

I say basically, because the constant moderate turbulence and kicking, gusting winds made airport and runway scene jumble and swerve around out the windscreen eight miles ahead. Philly has three runways aligned in the same direction and an old runway in use as a taxiway, and I admit that in the turbulence it had taken a few seconds to find the right one. By this time, we were relieved to verify that the landing gear was ‘down, three green’ and the nosewheel steering was still ‘on-line’ (its ‘steer by wire’).

I was a bit out of our element at this moment, but knew what to do – fly the plane, and how to do it. We were at a very light weight, and I had the thrust at a setting I thought would counter the strong headwinds buffeting us from the right side. But a series of gusts at this altitude, 1,500 feet above the ground, kept us from joining the glideslope (we were a little high) and slowing to the proper speed for a few more seconds. “Chop and drop” occurred, as they say, but only for a little bit, we were soon configured, on glide path, and ‘stabilized’ (as much as you can be in 20+ knot gusts) with the thrust ‘up’ by 1,000 feet AGL.

The exact wind report on the ATIS was 330 degrees at 25 knots, gusts to 32. The math on that works out to a crosswind of 60 degrees and a crosswind ‘factor’ of about .87, or a crosswind component of 22 knots, gusting to 28.  The maximum demonstrated landing crosswind component for our CRJ200 is 27 knots, so this was pushing it.

Its unnatural, well, it looks unnatural, to be pointed away from the runway, into the wind, flying sideways in a strong crosswind, but that’s how birds do it and that’s how man does it. Any seasoned pilot has landed in some strong ones, and this one was impressive, intimidating even. With our nose cocked twenty degrees to the right of the runway, the touchdown zone loomed into view.

“100 - - - 50 – 40 – 30 – 20 - 10”. The automated voice called out our radar (airplane based) measured altitudes down to the ground. At the fifty foot call I had the thrust levers coming back and felt them reach the idle stops by twenty. At that moment I applied a healthy amount of left rudder pressure and right control wheel pressure, and had already applied back pressure to start the flare.

Our empty and gust buffeted jet, save the three of us, gyrated on all axes, its right wing now banked low against the ground, with the nose aligned with the centerline of the runway and pitching up to permit the main landing gear to touchdown first.

The CRJ has a fairly low wing and the wingtip and/or wing flaps has a good likelihood of scraping the ground when touching down in a bank angle of ten degrees or more. I’ve never really been afraid of this occurring in a crosswind, although it’s happened before at our airline. In strong crosswinds a cautious “pilot not flying” monitors the bank angle on touchdown and advises when it reaches ten degrees. This frees up the landing pilot to completely focus on landing.

In the moments over the runway I kept increasing control deflection as our airspeed was decreasing, till I had full left rudder in and lots of right aileron. Then, just a hair before we touched down, inexplicably, I relaxed the aileron pressure, enough that the wings returned towards level. Oops. I don’t know how many strong crosswinds I’ve landed in, but it’s been a very long time since I’ve done such a ‘fool’ thing as this. I think that in this wind I was concerned about the wingtip and flaps, and ‘gave up’ too soon. The aviation axioms I failed to fulfill in this instance is to ‘fly the plane till every part stops moving’ – don’t stop flying the plane. In a flash, literally, I watched the runway slide over to the right fifteen feet, right as we touched down, not hard however, wings basically level, with the four main gear tires spinning up, smoking and sliding across the grooved runway surface. I had let the wind win, and it had pushed us across the runway, downwind (I don’t call it drifting).

I put the right aileron pressure back in instantly, lowered the nose to get the steering wheels on the ground, pulled the thrust levers into full reverse, applied the main wheel brakes on the rudder pedals, and muttered questioning and un-congratulatory words to myself. Steering the plane back to the centerline using the rudder pedals isn’t that difficult, once the other proper controls are applied, I relearned.

During our taxi in the tower updated that at our moment of landing the wind was now blowing at 31, gusting to 40, and I believed it. That was equivalent to a direct crosswind of 27 knots, gusting to 36, as much as we are allowed to do and as much as I want to handle in a CRJ. We parked next to the maintenance hangar, told the mechanics they could have it, and braved the gale in a short walk to the concourse to resume our scheduled day.

Landing in strong, gusty crosswinds bug piston and turbine engine pilots (especially at the lower levels of experience) both practically more than any other issue involved in flying planes. It tends to be black and white too, you either are comfortable or you aren’t. The problem if you’re not is that you have to go out in it and get exposure to the windy, gusty conditions to increase your proficiency and confidence in them. It is a major practical and mental barrier to pilot confidence and competence, and a major cause of minor incidents and accidents. Crosswind proficiency should be mastered at the lower levels of aviation and training. It takes courage to go conquer crosswinds with an instructor, and even more to do so by yourself. But when you relish the opportunity to meet the challenge and find yourself alone in the traffic pattern, battling them and ‘winning’, you enjoy a great feeling of accomplishment and satisfaction, because you know you will carry that confidence and proficiency with you the rest of your flying career.

God bless you, and thanks for reading my blog. He Loves all of us, you know!

1 comment:

Bas said...

Hello Craig,

What a great story, thank you! I'm addicted already haha.