Air Traffic Control

GCA is a landing aid whereby a controller used radar to talk pilots down in bad weather. The GCA unit at Marville consisted of two trailers situated beside the runway about halfway between the approach ends. One trailer housed the auxiliary diesel generators, the other the radar and the controllers. There were three controller positions, each with two radar scopes. One scope was the PPI (plan position indicator), the other the PAR (precision approach radar). The PPI was atop the PAR and gave a plan view of the area surrounding the station. Its scale could be changed from 5 miles to 30 miles for solid returns (blips), and 200 miles for electronic returns (squawks). We used the PPI to direct aircraft onto the PAR for final approach, but it could also be used for a non-precision approach. On a PPI final the pilots was given steers to maintain a centreline, and he was told his distance from the runway and the altitude he should be passing through. Using this information the pilot would adjust his rate of descent to maintain a three-degree glidepath. As it was not as accurate as PAR, the limits were higher. If he was not visual at 500 feet/1 mile, the pilot was required to carry out a missed approach procedure by climbing to a prescribed altitude and homing to a radio beacon. He could then try again or land elsewhere, depending on his fuel. Because of its limitations, the PPI approach was only used when the PAR was unavailable. The PAR was so accurate that we often brought aircraft in well below the limits of 200 feet and a half a mile visibility.

The PAR consisted of two scopes in one. The upper indicator had an electonic inscribed glidepath, and range marks, while the lower had a centreline and range marks. At 10 miles from the runway and a few degrees either side of the centerline, the aircraft would enter the PAR. The controller would give the pilot steers to maintain the centerline, tell him when to start down, then ask for changes in the rate of descent to maintain the glidepath. Once on the glidepath, the controller would begin a continuous talkdown which, if interrupted for five seconds, would require the pilot to execute a missed approach procedure.

Periodically, the controllers had to undergo flight tests. These consisted of two normal approaches and one emergency. If he was not sharp, the controller could be assigned higher limits or have his limits taken away. Unfortunately a few controllers could not take the strain and were taken out of Europe.

We called an approach "a run", and we used three letdown procedures: a beacon approach, a GCI/GCA handoff and a square pattern. On the beacon approach the pilot would descend from the beacon, start a turn toward the runway at a prescribed altitude and call GCA. We would pick them up on the PPI and direct them to the PAR for the final approach. The GCI/GCA handoff required coordination between the GCI (ground controlled intercept) controller and the GCA controller. GCI would position the aircraft on the PPI scope, report its position, heading and altitude to GCA, and hand it off. We would begin the approach from that position.

Square patterns were usually used for practice or to direct the aircraft around to the other end of the runway for a PPI approach if the PAR was not into wind. A square pattern had the advantage of allowing the pilot and/or controller to practice many approaches without necessity of the pilot climbing to high altitude for a beacon letdown.

The PAR could only serve one end of the runway. Someone came up with the idea of turning the trailers 180 degrees so that the PAR could serve whichever runway was into wind. We began to experiment with towing the trailers onto the runway, U-turning and positioning them facing the other way. This required teamwork on our part, because the trailer had to be levelled with jacks and the radar calibrated. We got quite proficient at quickly changing runways. Then, one day the station CO arrived with a distinguished visitor to show off this innovation. Everything went well until the tow truck broke down, stranding the trailers on the runway. This effectively closed Marville, with its one runway. The embarradded CO turned to a corporal. Perhaps with dreams of promotion dancing in his head, off ran the corporal toward the stranded trailers, but he abruptly stopped when it came to him that he likely didn't have the muscel required to move the mighty GCA trailers. Despite this fiasco, we continued to turn the unit when required by wind direction.

One day we were caught with our PAR turned the wrong way. One of our Sabre squadrons was returning from Sardinia, and Europe was socked in. We were at minimums and the Sabres, which seemed to be chronically low on fuel, were reporting fuel states which would allow one approach and little more. We brought them in on PPI and prayed that there would be no missed approached. Everyone was recovered without a hitch, and we sat back to wait for our "pat on the back". What we got instead was a blast for not having the PAR available.

Because of our training and the high calibre of the pilots we controlled, our task was not normally difficult. It did require steady nerves because of emergencies and unusual situations. I recall one "hairy" day when we were at limits. I was traffic director, which meant that I directed all aircraft on the PPI and the PAR where I could hand them off to two final controllers. The Sabres were streaming off the beacon; GCI was handing off a section of CF-100s; and I was trying to fit an Expeditor into the pattern. The GCI had another handoff for me, a T-33 towing a target that could only turn in one direction. At times like this we earned our pay.

I brought aircraft in under all sorts of emergencies, including an engine fire. It could be rather difficult to talk with your heart pounding, and realizing that an error could cost lives. Such was the case with a Sabre one day. The pilot had been practising square patterns when a fog bank moved in. He radioed that he'd land on his next approach if it looked too bad. At three miles from touchdown I reported to him that the pilot ahead of him landed with half a mile visibility. He then decided to land immediately.

At half a mile on final, the Sabre blip was on the glidepath, a shade left of centerline. I had just given a two degree correction to the right when I saw the blip turn sharpley left, so sharp that it couldn't possibly be corrected for and complete the landing. I told the pilot to overshoot and acknowledge, then watched in horror as the Sabre swung back right and left again where its blip merged with that of the operational readiness point hangar. The ORP was just to the side at the end of the runway and housed a pair of CF-100s on alert. I dashed to the door to see the results, expecting a fireball, but the fog was so thick I couldn't see beyond our own antennas.

As the tower couldn't see the runway, they were unaware of anything unusual until I called them. I was soon relieved to hear that the Sabre had missed the ORP - it had crashed, but the pilot had survived. He had looked up at half a mile and by the time he got back onto instruments had gotten disoriented. He just missed the ORP and struck the ground heavily, bouncing and breaking apart. The last bounce may have saved the pilot's life, as he ended up atop an embankment instead of striking it head on. The Sabre had flown below GCA limits, but that was not uncommon. He just happened to get caught. Had we known just how bad the fog had become, the pilot would likely have stayed on the guages and landed OK.

I once told the pilot of a Dakota that if he was not going to take my corrections he should go back to tower for a visual approach. The Dak was all over the sky and to continue the approach would have been useless. The pilot apologized, saying that he had been flying a desk too long. I later learned that he was a senior Air Div officer, but he was also a gentleman.

The highly trained radar technicians were an important part of our team. They kep the equipment working and put up with our nagging. One day a new tech, who was fresh from his course, told me he couldn't get the radar to come on and that he was going to call the sergeant since he had tried everything he knew. I took him into the trailer, where I turned on the high voltage power supply. I then kicked it and the radar came on immediately. Some things just weren't covered in the manuals.

After my tour at Marville I returned to Canada, working at training stations on the Prairies. After Europe, both this work and the landscape were boring, so I left the RCAF in 1963 and took up a career as a police officer in Toronto. In 1979 I revisited Marville, and although the control tower and barracks were still there, this once vibrant flying base was now just a public works yard. On a 1981 visit to Trenton I toured the air traffic facilities. To my surprise I discovered that the same equipment I had worked at Marville in the fifties was still in use. Like me, it was 30 years older, but its modifications were an improvement. I couldn't say the same for my own! Today I hold a pilot's licence with an IFR rating, and often wonder about those pilots in their single-engine Sabres flying in all that bad weather. I'm glad that we in the flying control business were there to help them with their job.