Tuesday, October 24, 2006

Excessive Energy

The four operational scenarios that I worry about every flight are:

1. Catastrophic engine failure at a critical moment during take-off.
2. Excessive energy (velocity) at landing leading to an overrun.
3. Severe turbulence, either expected (storms) or unexpected (clear air turbulence).
4. Fire on the ground or in-flight.

These scenarios have to be controlled at all costs, or the consequences can be ugly. Number three is the hardest to control, since we must go on our flights, no matter the weather. Yeah, we will delay a bit here and there, cancel a flight every now and then (but the next one will go), or will be snowed under in Boston, but we are going, one way or the other. Managing number three takes experience; number one, two and four can be taught, tested, and drilled over and over until it is second nature.

The problem comes with the old saying familiarity breeds contempt. Modern airliners are reliable beasts with good safety records. This leads to thinking about that good looking flight attendant in the back rather than what will I do if number one engine turns into hot shrapnel at 160 m.p.h. or where could we land right now if the rear galley catches on fire?

Last night, we got a good look at worry item #2. My co-pilot, a young and sharp kid whom I have flown with many times, was the flying pilot enroute to Connecticut. The flight eastbound was smooth and fast. Our average tailwind was over 130 m.p.h. putting us into the Hartford area forty minutes ahead of schedule. The co-pilot was doing his usual good job and I was expecting an uneventful landing.

Even so, I am always looking for little uh-ohs that might become big Uh-Ohs. I noticed we were really moving across the landscape as he was descending to intercept the radio beam that leads to the runway. I checked the inertial navigation platform digital readout; a 40 m.p.h. tail wind at 3,000 feet. Our airspeed was 200 m.p.h. and slowing but our groundspeed (also energy state) was quite a bit higher at over 240 m.p.h. The co-pilot started calling for landing gear and flaps, which I selected and checked. We were fully configured for landing at 1,000 feet with an airspeed of 160 m.p.h., but a ground speed of 200 m.p.h. Still a 40 m.p.h. tailwind pushing us toward the airport. The descent rate was way too high, because the faster the aircraft is crossing real estate, the faster it has to lose altitude in that given distance. We had a perfect scenario for a runway overrun; too much energy to lose and not enough pavement to do so. It's an insidious problem that has caused a lot of heartache... Energy increases with the square of the speed increase.

The control tower guys were reporting a crosswind of 10 m.p.h. on the surface, quite a change in only 1,000 feet vertical distance, but in no way uncommon. At 800 feet above the ground, the co-pilot turned the whizbang stuff "off" and selected emergency flight controls (stick and rudder) to make the landing. At 500 feet, the wind still at 40 m.p.h. on the tail, began to abate and rotate off the tail. Too late, though... Our groundspeed was too high. The co-pilot was watching the situation and said' "This isn't looking good skipper."

I agreed with him and suggested a go-around for another runway with favorable winds. The co-pilot raised the nose to intiate a climb, at the same time pushing the thrust levers forward to maximum go-around power. Holy Moly! We were shoved back into our seats as the engines transitioned from idle thrust to maximum go-around thrust. The fuel flows went from 800 lbs. to north of 10,000 lbs. Might as well cut a six inch hole in the bottom of each wing tank. The co-pilot called for "landing gear up, flaps to 18 degrees."

The control tower cleared us to land on a more wind friendly runway. In my best Captain's voice, I assured the folks that everything was OK and gave them the short version of why we did not land on the first attempt. A few minutes later, the co-pilot pulled the reverse thrust levers up and over to open the cascade vanes; the aircraft's nose lowered significantly as it morphed from an agile flying machine to an ungainly ground vehicle, via reverse thrust, wing spoilers, and wheel brakes.

The go-around took 12 minutes and 2,000 lbs. of fuel... A small price for a safe landing, though.

Day number two of a four day is done. Tomorrow night; Anchorage. Life is good!

13 comments:

Stu Savory said...

Let's see if I've understood this correctly. So if you came in on the reverse course the HEAD wind would drop by 40 knots in the final 500 feet. So isn't there a danger of stalling it in due to too LITTLE energy? With that amount of windshear I'd want to come in on the reverse course rather hotter than usual?

Neil said...

Dave, another great post......

I was reminded of something my Dad (fellow pilot) told me once that stuck with me. Of course, even in my little Tomahawk I have to think over what *could* happen, although my list of things that could fizzle and break is obviously alot shorther than yours in the Bus. He put it into 4 words for me. "Is today the day?" Engine failure on takeoff, forced landing, quick moving ugly weather..."Is today the day?"

I think that to myself everytime im taxiing onto a runway. : )

Amyway, one question...you refer to the phase of flight when your FO disengaged the AP as "emergency controls." Is this the same as regular hand flying controls, or is there a difference?

Thanks

dave said...

stu, yep, it would be a problem if you lost the headwind instantly. In that case it would be easier to recover from a low airspeed airborne scenario, than trying to stop on a short runway because you landed too fast.

dave said...

neil, we jokingly refer to manual flight controls as emergency flight controls. The 320/319 flies lovely with stick and rudder/manual thrust, but the guy who signs our paychecks likes the magic on as much as possible; it's more fuel effecient.

Anonymous said...

Dave, I have been following your blog for a really long time now. Im a Student Pilot at Dominican Republic, I remember once, in our now closed local airport Herrera, it has a relative short runway a corporate jet landed, I dont remember the model but it was a lower wing jet, wich you know make faster approches even thou in dirty configuration, after they crossed the 50 feet obstacle in the approach they touched as fast as a comet, I remember everybody, firefighters ran, behind the aircraft, it was clear where it was going, it crossed the whole runway, and the airport limits and ended up in a street XD. It was so funny and sad the face of a driver of the car. No one was injured thanks god. Regards.
Victor.

Jack said...

2000 lbs of Jet-A for a go-around eh? Wow...another 600 lbs and it equals the max gros for my Arrow. Alot of fuel but as you say, well worth a safe landing.

Anonymous said...

Love the blog, love it.

I've been in one of those scenarios that you speak of - a fire in the cabin during approach to Corfu (Greece) airport - a fool passenger a few seats in front of us had gone to put their cigarette out in the armrest ashtray, and missed.

They ignored the fact that the cigarette was still burning inbetween their seats until clouds of smoke were spotted from behind - I've never seen flight attendants move so fast, nor did I realise we had so many of them on the flight - a few good squirts with an extinguisher and problem solved, ten seconds later we hit the runway in what I can only describe as "get this buggah down now" mode.

A good start to a holiday :)

smurfjet said...

Dave, I would like to read your thoughts about Mid-air collisions. Would they fit in your operational scenarios?

DailyAviator said...

"Emergency" flight controls. LOL...

Circe said...

I was totally at the edge of my seat reading this post. Oh. My. Good decision though as safety should be paramount.

Anonymous said...

David I forgot to tell you that honestly you have inspire me to began my own blog and I want you to check it out, and let me know if you allow me to get yours in the links section? URL : http://lifeinaviation.blogspot.com/

Regards,
Vic.

Noella said...

Whew! That's my adrenalin fix for the day!

Thanks, Dave. Just can't get enough of your writing!

Anonymous said...

This is my first posting to your blog, though I've read it all from start to finish.

This latest entry is the best. Informative, well-written, but above all suspensful.

Amazing...