Why Planes Crash: 2001: Why Planes Crash, #1

By Sylvia Wrigley

Air travel is one of the safest modes of travel when we take into account the distances and freedom that it allows us. And yet, we still remain obsessed with aviation disasters. What caused these accidents? Whose fault was it? In her series of books, Why Planes Crash, Sylvia Wrigley investigates the worst aviation disasters of the twenty first century.

Why Planes Crash: 2001 is the first of the series. Wrigley has put together eleven of the most interesting incidents that the world saw in the year 2001. These include detailed analyses of the disastrous runway incursion at Linate, the passenger interference leading to the Avjet Aspen Crash and why an Airbus A300 disintegrated over Queens.

From bad weather to the engineering faults in the aircraft, the author critically considers every factor that might have lead to the crash. Her investigations and deep insight compiled thoughtfully in this book allow the reader to act as a witness of the disaster and yet it is comprehensive enough for anyone with no aviation knowledge to understand.

"For those aviation enthusiasts that wish to delve beyond the sensationalist headlines on aviation accidents Sylvia Spruck Wrigley's "Why Planes Crash" will satisfy their needs. Informative, critical and insightful."
~HAL STOEN, STOENWORKS AVIATION

"The author has done a remarkable job in not only researching the evidence of the accidents she covers and in putting across the problems of an investigation, but she has managed to do this in a way that will interest and appeal to a wide range of readers."
~JOHN FARLEY OBE, AUTHOR OF VIEW FROM THE HOVER

• Language: English
• Publisher: Sylvia Wrigley
• Release date: May 7, 2013
• ISBN: 9781501418587

Book preview

Introduction

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WHEN I FIRST CONSIDERED this series, I knew I wanted to focus on modern failures. I’d been invited to London to speak on Aircraft Confidential, the Discovery television show highlighting famous aviation disasters. Many of the fascinating, frequently talked about aircraft failures like Aloha Airlines losing its hull or the fast spreading fire of Swissair 111 are lacking resonance for the flyers of today. They are historically interesting but not immediately pertinent to modern aviation. These are accidents which will not happen again, often as a direct result of the efforts of investigators of the time. I find them endlessly fascinating; however I am even more intrigued by real-world problems which we are still experiencing in aviation.

The question now is really: Why do planes still crash? By concentrating on modern crashes, we can focus on the issues of today and understand what can be done to continue to keep aviation safe.

It is often too easy to point at the pilot. He is a single point of failure who can be blamed without financial repercussion for the airline, without requiring lengthy legislative amendments by the governments, without requiring changes at manufacturing plants. A single reputation is destroyed, sure, but millions in man-hours and money are saved. That’s the efficient answer and, thus, the one we should arrive at only when the other factors have all been investigated.

This is not to say that pilots don’t make errors, or that those errors should be disregarded. However, when considering the incident, we should be asking ourselves what the reasonable repercussions of a mistake are. A pilot who gets lost in an airfield and queries his position should not be left to blunder forward onto an active runway. A passenger who insists that he must get in at all costs should not be able to pressure the pilot into reckless behaviour. And attending advanced training certainly shouldn’t result in bad habits being taught which put the entire aircraft at risk. All of these accidents and more are covered in the pages to come. Some are more technical than others and require more time to explain, but I am hopeful that every analysis is interesting to pilots and passengers alike.

This book covers eleven accidents and incidents which took place over the course of 2001. Each section includes text quoted directly from the accident report. If you’d like to read the original accident report for more information and context, then simply skip to the end of the section where you’ll find a link to the original report.

In each chapter, I cover the core chain of events which led to the accident rather than making a simple judgment. Accidents are invariably a combination of factors, and pilot decisions and (in)actions can be the result of a culmination of those factors. A strong investigation will not only consider the cause but the contributing factors: those actions or inactions which could have saved the day but didn’t. The objective in accident investigations around the world is not to cast blame, but to understand every aspect so that we can stop it happening again. Unravelling the mystery from the wreckage is the most important step.

Lost in the Fog

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THE CESSNA’S FLIGHT PLAN reported the crew as instrument rated for an approach down to a minimum visibility of 550 metres. At the time, the visibility at Milano Linate Airport was 100 metres with fog and overcast at 100 feet: much less than the flight crew required for a safe landing at that airport.

Cessna Citation 525. Photo by Noel Jones.Cessna Citation 525. Photo by Noel Jones.

Cessna Citation 525. Photo by Noel Jones.

Despite this, the Cessna pilot decided to continue. The controller on the Tower frequency, having warned him of the low visibility, cleared him to land on Runway 36R, the Pista principale.

There are two aprons—the manoeuvring areas of an airport where aircraft are loaded/unloaded and able to park. At Milan, the North apron serves the Pista principale for large transport-category aircraft. The West apron, next to the Pista turistica is available for the smaller General Aviation traffic using the short runway. Until fairly recently, it was easy to keep the two types of traffic separate. But as General Aviation aircraft have become more powerful, it has become more common for small planes at the West apron to require the longer Pista principale.

Illustration of the runways at Milan-Linate Airport. Photo by Simon Spruck.Illustration of the runways at Milan-Linate Airport. Photo by Simon Spruck.

Illustration of the runways at Milan-Linate Airport. Photo by Simon Spruck.

The airfield has with two runways that run north/south: on the right is the large runway with taxiways that connect it to the North apron. On the left, is the small runway with taxiways at the top and bottom. These taxiways start at the West apron and carry on past the small runway to the large runway. The main taxiway runs parallel to the Pista principale for its full length. Four connecting taxiways are numbered clockwise starting from the north. R1, R2, R3 and R4 connect the main taxiway to the Pista principale. These are used by the large transport-category aircraft using the North apron and are not all that important to our story.

The remaining taxiways do not follow the clockwise convention. Next is R6, which runs from the West apron along the bottom (the south threshold) of the Pista turistica and then continues to the mid-point of the Pista principale. Finally, R5 is at the top of the airfield, passing the northern thresholds of both the Pista turistica and the Pista principale to the North apron.

The German Cessna landed on Runway 36R (northbound on the Pista principale) at 04:59:34. The aircraft passed the intersection for TWY R6, which connects to the mid-point of the Pista principale. The pilot requested permission to backtrack so he could use that taxiway to proceed directly to the West (GA) apron.

D-IEVX: EchoVictorXray on the ground, we could do a short back-track, to turn off to General Aviation.

Tower: DeltaVictorXray roger, on the ground on the hour, report runway vacated on Romeo 6.

D-IEVX: I’ll call you on Romeo 6.

D-IEVX: DeltaVictorXray is entering Romeo 6, now.

So far, everything has gone well.

The Cessna had already submitted a flight plan for the next flight: 05:45 hrs from Milano to Paris Le Bourget with two passengers on board. Once clear of the runway, the Tower controller asked the Cessna to contact Ground Control, who are responsible for movements on the airport excluding the active runways.

About forty minutes after the Cessna made its request to backtrack, Scandinavian 686 (a McDonnell Douglas MD-87) contacted Linate Ground Control from the North apron, asking for engine start clearance. The commercial flight from Milan to Copenhagen had 104 passengers on board.

Scandinavian Airlines (SAS) McDonnell Douglas MD-87. Photo by Dean Morley.Scandinavian Airlines (SAS) McDonnell Douglas MD-87. Photo by Dean Morley.

Scandinavian Airlines (SAS) McDonnell Douglas MD-87. Photo by Dean Morley.

The McDonnell Douglas MD-87 was given a slot time for take-off at 06:16 hrs.

Scandinavian 686 commenced their ground operations. They contacted Ground Control, the air traffic controllers responsible for movements of aircraft around the airport, including taxiways and inactive airways. Scandinavian 686 received taxi-clearance at 05:54:23.

Ground: Scandinavian 686 taxi to the holding position Cat III, QNH 1013 and please call me back entering the main taxiway.

Four minutes later, the Cessna at the West (GA) apron requested start-up clearance and was given a slot time of 06:19 hrs for take off.

For a few minutes, the two aircraft were on the same frequency but then Scandinavian 686 contacted Tower, who control traffic on the runway. From this point on, the two aircraft were unable to hear each other’s calls. They had no way to know what the other aircraft was doing other than by looking out the front. In the early morning fog shrouding the airfield, that was no help.

Milan Linate Airport had clear procedures in place for low visibility conditions in order to keep the aircraft safe. What they didn’t have is an ASMI.

Normally, the key to tracking ground traffic at a large airfield is the Aerodrome Surface Movement Indicator (ASMI) radar which makes it easy to track the aircraft as they move around the airfield.

Milano Linate Airport was equipped with analogue ASMI radar but it was old and apparently was becoming unreliable. In 1994, the civil aviation Air Navigation Service Provider began planning for the installation of a new radar system.

The project became stalled in 1995, with concerns raised about the costs. The airport was advised to avoid the acquisition of equipment that would become obsolete in view of the rapid technological development in this area. In other words, don’t replace the unreliable system with a new one, because a newer new one in a few years might be better and then we’ll have to buy another one. This is a common issue with new technology but most people go ahead and take that risk at the point when the need for a replacement becomes desperate.

In November 1999, a Notice to Airmen (NOTAM) was released that the ASMI radar was out of service. Two years later, on the 8th of October 2001, Milano Linate Airport still did not have a functioning Surface Movement Radar.

Airports not equipped with ASMI radar have three conditions of visibility for low visibility operations.

Visibility 1: visibility sufficient to taxi and avoid collision with other aircraft/vehicles on TWY and intersections by direct visual observation, and for ATC operators to exercise visual control of all such traffic.

Visibility 2: visibility sufficient to taxi and avoid collision with other aircraft/vehicles on TWY and intersections by direct visual observation, but insufficient for ATC operators to exercise visual control of all such traffic.

Visibility 3: visibility not sufficient for pilots to taxi autonomously and for ATC operators to exercise visual control of all such traffic.

In Visibility 3 conditions, departing traffic should be assisted by a FOLLOW-ME vehicle. All traffic would halt when the runway was in use.

The aircraft would only taxi when landing traffic had reported arriving at the parking bay and departing traffic had already taken off.

In other words, if Milano Linate had declared Visibility 3, the Cessna would not have taxied to the runway until after Scandinavia 686 had departed and would have had a lit vehicle to show the way.

At the time, the decision to declare Visibility 3 conditions was based on reports from the pilots. The controllers had no other method for taking this step. Only when a pilot thought to report that visibility was so bad that he could not taxi safely would the airport declare Visibility 3.

The