City of Tempe Propositions 301, 302, and 303

contributed by Toby Duffell

The Coyotes, V1, V2, and You

It was the end of a long week in New York city at the engineering company where I worked. Daydreams about the coming weekend floated in my head, the untouched draft report on my lap, a markup pen idle in my hand. Returning to Phoenix Skyharbor aboard a United 757, nothing seemed out of the ordinary – it was a bright, calm Friday afternoon as the craft crossed the outer marker coming in to land. But as the airplane arrowed in above the scores of tire marks left from first contact by previous landings there was a steep, sudden drop in altitude followed by a scream from both the Rolls Royce engines as the airplane abruptly nosed up. The runway seemed awfully close, awfully quickly . . . sitting towards to the front, I could hear alarms sounding in the cockpit above the rong-rong-rong of twin engines laboring to provide additional thrust. An unfortunate lady in business class cabin crew forgot herself and exclaimed shit! We had experienced a weather condition called wind shear, an invisible killer that can suck the lift from an aircraft and can cause it to pancake onto unforgiving blacktop, with damage ranging from undercarriage collapse, impaired control surfaces, through to loss of the hull. This is a nightmare for pilots and their training is to get the hell out. Forget about landing, engage maximum thrust, gain altitude, landing gear up, don’t attempt to turn.

Not everyone was as lucky as me and the flight I was on. As early as 1985, Delta flight 191 crashed on final approach to the Dallas-Fort Worth International Airport due to wind shear. A total of 135 people died in the accident, including 126 of the 152 passengers on board, 8 of 11 crew members and even a motorist on the ground. In the last 25 years, there have been 27 crashes due to wind shear. It’s not a matter of if instead it’s when. So given this inevitability, the concern becomes if it’s going to happen, how best can it be escaped from safely? In other words: How can we avoid threats to surviving shear? An aircraft experiencing a sudden loss of lift due to windshear above the proposed obstacle of the Coyotes stadium at the edge of the airport could be a disaster from which most or all on board may not escape. Add a capacity audience and we could experience the worst disaster in aviation history. You wouldn’t want to be there.

Another scenario that keeps Civil Aviation Captains and their First Officers awake at night is engine failure on takeoff. Termed EFTO this is the time when the engines encounter their most taxing conditions – by working the hardest to get the craft airborne from a standing start. The pilot spools up the engines to takeoff thrust, releases the ground brakes, and the airplane is propelled forward with the plan of passing V1 (the speed beyond which takeoff cannot safely be aborted) as quickly as possible through to V2, the takeoff safety speed when getting off the ground and avoiding obstacles is possible. Engine failure between V1 and V2 results in the flight crew on board having to try to take off. There is no alternative – remaining on the ground would result in “running out of runway” and a collision with whatever lay beyond the stopway area at the end of the runway. So what are those in control of the craft trained to do? The instinct to turn around and circle back should be avoided – that risks the craft losing speed, slipping into a turn and further losing altitude. If the Coyotes stadium lies before a crippled aircraft the design gap – the separation between the structure and an aircraft with an engine out – is thirty-five feet. Meaning, that the craft could pass within the length of three automobiles from the top of the stadium. With a wet runway, that gap can reduce to fifteen feet. Now add gusting, or windshear, or bird strikes affecting both engines, or a second’s indecision in the cockpit and there could be a disaster. Add a capacity stadium and there could be a tragedy.

So yes, I am opposed to building a high-capacity stadium with a thousand attendees directly under the flight path of heavy commercial airliners taking off or coming in to land. I am also opposed to building high-density apartment blocks with thousands of dwellers in the same place. Like you, I don’t want to be in a commercial jet barreling down on a stadium. And I don’t want to be in that stadium, either, or anyone I know. Or anyone I remotely know. Or anyone at all.

So why is this proposal before the voters of Tempe? Has Mayor Corey – whose signs were up in my front yard, whose fund-raiser I attended, and for whom I ultimately voted – has Mayor Corey been dazzled by the prospect of a glamorous political win? Are the local Urban Planners who call the project “Voterville” or “Coreytown” being cynical? Is Mr. Woods looking to beef up his resume in furtherance of his long-term political aims? There’s nothing wrong with that – we should all be allowed to realize our ambitions. But, given the risks, isn’t there a safer way for him to do it?

Editor’s Note: Toby is a licensed engineer with several decades of experience in military and commercial systems including those for the USAF, RAF and civilian ground-based transportation systems. He co-authored “National Design Standards and Safety Guidelines” which has been translated into German, French and Chinese. He is a Senior Member of the IEEE in the USA, and held licensure in the UK and Western Europe.