Reminicences # 4 Pete Clarke : Memories of 9/11

Born in Lytham I started my career as an assistant at Barton Hall, the Northern Air Traffic Control Centre. I trained to become a controller and was posted to the radar station responsible for controlling the high level jets which can be seen criss-crossing the skies over the north of England. When this unit closed in the 1970s I was posted to the Scottish and Oceanic Control Centre. In total I spent 30 years working as an Oceanic controller at the Shanwick Oceanic Control Centre, Prestwick, Scotland. I moved south after 10 years for a short period to work as an Instructor at our College of ATC before returning to Scotland. After 40 years service in ATC I retired home to Lytham St Annes.

Flights over the North Atlantic Ocean between Europe and America or Canada are controlled in an entirely different way from those over the land masses of those continents. The controller wearing a headset and sitting in front of a radar screen in instant VHF (Very High Frequency) radio communication with aircraft is how most people think of Air Traffic Control. Once out over the vast expanse of the North Atlantic the aircraft are beyond both radar and VHF radio cover. Radio communication is via a long range radio station using HF (High Frequency) radio. This radio station, based in Ireland, near Shannon airport, relays the messages to the controller for action. (Today, most communication is by electronic datalink where the controller can send a computer message directly to the flight deck computer in the aircraft).

The Oceanic controllers at Prestwick control all the flights crossing the Atlantic Ocean between 45deg. North and 61deg. North. – Just North of the northern coast of Spain to just South of the southern coast of Iceland. The routes for the flights change each day to avoid the worst of the westerly headwinds and are generally spaced 60 nautical miles (nm) apart. The controllers keep the aircraft separated by clearing each aircraft to fly on a route at a specific altitude and speed to ensure they remain clear of the other flights until they reach radar and VHF cover approaching Canadian or American airspace. The Shanwick Oceanic Control system has been fully computerised since 1987. All the flight data is recorded and displayed on a computer screen for each controller. The controller has no visual aid to determine the position of a flight other than the reports from the aircraft and reference to maps displayed above them.

Due to the time differences either side of the Atlantic Ocean most flights at night come eastbound to arrive at their European destinations around 8 o’clock. Conversely, westbound flights depart early or mid-morning to arrive late afternoon on the western side of the Atlantic. In 2001 approximately 1,000 flights crossed the North Atlantic daily.

By the time the aircraft have reached the Oceanic airspace boundary they have climbed to their cleared cruising altitude with the cabin crew preparing to serve drinks and meals to the passengers as they settle down to relax on the long flight.

There are 2 phases to controlling Oceanic flights. About 90 mins. before reaching the airspace boundary the pilot or co-pilot will contact a Planning controller to request a cleared route across the Ocean. When the aircraft reaches the Ocean boundary 90 mins. later the crew will make position reports to the En-Route controller as they pass each 10deg. of Longitude, i.e. 20deg West, 30deg. West, etc. These are approximately 40mins. apart and enable the controller to confirm the aircraft is flying on the correct route on time and is therefore still separated from the other flights.

As the flow of flights increases the En-route controller may be handling up to 60 aircraft on his or her sector. The airspace is split vertically with 3 or 4 sectors handling flights at different levels.

My duty that day, the 11th September 2001, was to start my shift at 10 a.m. I was joining colleagues on the morning Watch just as the westbound traffic flow was starting. With the increasing traffic load it would be a busy morning ahead. Controllers would work for a period of one to one and a half hours then take a break. It may be a busy session as a Planner then return to another planning sector or give a break to an En-rout controller. By 11.30 the traffic is reaching its peak on the Planning sectors with the controllers very busy trying to find clear routes for each aircraft, so lunch-time is a welcome break. Lunch over and that peak of traffic is now entering Oceanic airspace as the westbound flow speeds towards Canada and America at 7 to 8 miles per minute. I was now taking my turn as an En-route controller. As the clock ticked past 2 o’clock my thoughts drifted towards my own Watch colleagues arriving soon at 2.30 when I would be due a well-earned break.

It was now about ten past 2. The morning shift Supervisor was taking his break after the morning planning rush. The rest room has a TV and is across the corridor from the operations room. The Supervisor came into the operations room and wandered over to the controllers to say that he had heard a report of an aircraft crashing into one of the twin towers in New York. Our initial thoughts were that it would probably be a light aircraft of some sort lost in the early morning mist that sometimes covers the tops of the city skyscrapers. We were then given a second report that it was a jet aircraft, but again thought that maybe it was a small executive jet.

Before any more discussion could take place my telephone rang. It was our HF radio station at Ballygireen alerting me to a “Mayday” message they had forwarded to me. An American Airlines flight was requesting immediate return to London.

Emergencies with transatlantic passenger jets are not common but do happen, usually due to a sick passenger or a technical problem indicated by a warning light in the cockpit. Controllers train for such an emergency and both the flight crew and controllers have procedures to follow. The controller will search for a clear route for the flight to return on. It may need the aircraft to temporarily position between 2 of the routes at an intermediate level of 500ft. It will not be completely separated from other flights on the adjacent routes initially but it will be 30 nautical miles away. In due course a fully cleared route will be established by moving other flights out of the way.

While still dealing with this “Mayday” another comes in to an adjacent sector, then another. What’s going on?

A plan needed to be formed quickly. – Descend the emergency flights 500ft and turn left to position between the westbound routes but check with the sector handling the airspace below, if necessary, and watch out for other flights turning back which may not be as far west. Remember, the controller cannot see where each aircraft is. The computer screen records the position and altitude of each aircraft as it passes pre-determined points (20deg. west, 30deg. west, etc) on it’s route. The controller uses this information, as necessary, to plot the aircraft’s position on a map.

Telephones are now buzzing. Control of the aircraft passes to the Canadian Oceanic Controllers at Gander as they reach half way across the Ocean at latitude 30deg. west. For many aircraft which have departed from European airports this is also the point at which they have used up more than half of their fuel. Some of these flights also requested immediate turnback to the UK or Ireland but it would require coordination with the Canadian controllers to agree a course of action.

The message is now coming in that two American Airlines aircraft have hit the twin towers and that the USA is closing its airspace to all flights and telling those that are already in their airspace to land immediately at the nearest airport. How many more American Airlines flights could be hijacked?

The Canadian controllers now have a big problem on their hands too. America is not accepting flights into their airspace so any flights in Canadian airspace must now be diverted to a Canadian airfield. Halifax, Gander and St. Johns near the east coast suddenly become major diversion destinations.

The situation has become very serious. All domestic air traffic control centres are instructed to stop any flights from entering Oceanic airspace. The Oceanic Planning controllers also stop issuing clearances to any further flights heading for American airspace. Some of these flights will return to their departure airport, others will divert to Prestwick or Shannon or any other suitable airport that can handle them.

It is 2.30 in the afternoon and time for a Watch change-over. The incoming Supervisor is briefed along with the sector controllers to ensure they have a full understanding of the plan before taking over control. This is a chance for 1 or 2 day-shift controllers to take a break. Normally, a controller may work a sector for 2 hours before they must take a break but in this situation, with such a high concentration level, a break will be given after about 45 minutes. Some extra controllers who live locally are called in to help too.

As one of the more senior experienced controllers I hand over my sector but stay behind the bank of controllers to monitor them and offer assistance, as required. We still have some flights heading westbound who have not yet asked for a diversion so each of them is contacted with a discrete message suggesting they contact their company for further instructions.

The Oceanic controllers are now working far beyond their normal limits. Each flight is asked for an updated position which is entered into the computer along with the new route. Hopefully the controller has managed to find a fully cleared route away from the other flights also returning. Updating this data enables the computer to send flight details to the relevant domestic control centre but some flights are too close to the boundary for the data to be updated. These flights are told to contact the domestic radar controllers as soon as they are in VHF range to ensure they have their details.

COBRA (Cabinet Office Briefing Room A, the ministerial-level emergency committee) is convened in London. They must be briefed by the Centre Manager. A team of senior staff is gathered in our conference room monitoring the situation. The Operations Room is too busy to accommodate anyone other than essential personnel. Periodically, I am asked by my Supervisor to brief our senior staff who then brief COBRA.

By 4 o’clock nothing is heading westbound towards American airspace. Some flights still have a long way to go before they reach the eastern boundary of our airspace and back into the relative safety of radar cover but the plan seems to have worked. By 6 o’clock all is becoming quiet and the controllers can finally breathe a sigh of relief.

Somehow we managed to turn back nearly 100 aircraft without a single one coming close to another. We passed all these flights to our adjacent domestic control centres who took control to guide them to their chosen destination. We did it without a single word of complaint even when some flights called up those centres before the controller could pass on their details.

The extremely difficult task performed that day by the Shanwick Oceanic Controllers was recognised by the aviation industry and other ATC control units, with an achievement award, for which we were all very proud.

I arrived home about 7 o’clock that night to join my young family. I finally sat down in front of the television to see the horror that had unfolded that day and realised the major part we had to play.

I returned to work the next day to a very different operations room. Hardly any flights were operating other than to destinations well clear of American airspace. It gave us all time to sit around and discuss how we had achieved what, until the day before, we would have considered impossible.

Over the next few days we heard more stories from that day.

I saw a time lapse video of the American airspace showing how quickly aircraft were ordered to land until the only aircraft left airborne were a few military air defence jets.

I also saw an aerial photograph of Halifax airport. Every possible piece of concrete was covered by aircraft apart from the main runway. Those on the secondary cross runway were parked either-side of the centre line with wings overlapping like a zip. After several days authorisation was given to re-open US airspace so crews returned to collect their aircraft. When one crew were asked which one was their’s they were told to “come back tomorrow” as there were quite a number that would have to be moved first!

I have since visited New York and the site of the Twin Towers and paid my respects to those who died, at St. Paul’s Chapel of Trinity Church, adjacent to the site.

It brought back so many memories of that day and the affect it had on so many people around the world.

Pete Clarke

Shanwick Oceanic Air Traffic Controller

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