Happy Landings.

One of the things that an aviator has to face when he takes to the air is landing and stopping when the flight is over. If the aircraft is unable to stop because the brakes have failed or there is an aircraft malfunction or an emergency which prevents the aircraft from stopping the results could be catastrophic. There would almost certainly be some aircraft damage and maybe some injury, or in an extreme case, an injury which was fatal.

With the advent of the jet engine, in the 1950’s aircraft became faster and so landing speeds became faster and if an aircraft failed to stop on landing the consequences could be more serious. Action was taken to try and alleviate this problem and as a result tests were carried out to see whether the method used on aircraft carriers to stop aircraft by the use of arrester wires could be adapted for use on land. Naval aircraft operating from carriers were normally fitted with an arrester hook at their tail end which was lowered by the pilot as the aircraft made its approach for landing. Across the ship’s deck from port to starboard were laid a series of separate wires so that they were at right angles to the aircraft’s line of flight as it approached the ship. As the aircraft landed and moved forward its hook engaged one of the wires, pulling it through it through its housings, one on each side of the deck, so that the arrester wire lengthened as the aircraft moved forward. There was a retarding device attached to each end of the arrester wire which governed its speed by gradually increasing the load on the aircraft’s forward progress and eventually the aircraft was brought to a stop.  The procedure worked well, even if the aircraft had a brake failure or otherwise malfunctioned and in these circumstances the aircraft was generally recoverable. Should an aircraft fail to catch a wire then it would be stopped by a net which was deployed across the deck to catch it. This was in the days before the angled deck was introduced, which enables the aircraft to take off and try again. The net thus became obsolete.

The system was well proven and worked well with the additional advantage that the pilot would normally be familiar with deck landings so would be able to cope in the event of there being an emergency landing. Because of this there didn’t seem to be any reason why it could not be adapted for use on land. Laying the wires and their fittings should be a simple operation but the method of slowing the aircraft down needed some thought. The final solution was tested together with the complete land based arrester system and the proposed system for slowing the aircraft fulfilled its promise and all the calculations worked out so it was decided to fit the total system with the anchor chains at HMS Heron, RNAS Yeovilton, which was a fully operational air station.

The method of slowing the aircraft was resolved by using anchor chain. It was heavy, readily available from the dockyard and could be laid in position by using cranes and detached and reattached to the arrester gear as the need arose. A length of chain was laid on each side of the runway in the form of a U with the legs lying side by side down the length of the runway with the bend at its beginning. The arrester wires were attached to the leg of the chain nearest the runway and were designed to be readily detachable in the event of an emergency and to be reattached when the arrester set up was remade once the aircraft had been recovered and the site made good.

After the experts had completed their calculations and tests and were satisfied that the land based arrester system was acceptable and would function as designed and planned, arrangements were made to demonstrate it at Yeovilton. On the due date lorries arrived carrying the chains from the dockyard together with the arrester wires and attendant equipment which were deposited on site and checked, and all was made ready to proceed with the demonstration. This was to take place at the chosen runway with a standard operational aircraft from one of the squadrons based at Yeovilton and a regular squadron pilot who had been fully briefed about the exercise and its objective. The demonstration was to be watched by members of the admiral’s staff plus representatives from each of the squadrons stationed at Yeovilton as well as from Station Workshops, including anyone who was likely to be involved in crash and salvage operations. There was a general briefing, everyone was told to stand well clear and the process started.

The arrester system was put in place and the chains laid and attached, with everything being checked against detailed drawings. The aircraft was positioned at the end of the runway with its nose pointing down the runway so that it could pick up a wire once its arrester hook was lowered. Its engine was started and it was given the signal to move and drop its hook to simulate an emergency landing. The aircraft did so and almost immediately picked up a wire in the approved manner.. As it moved forward the chains started to move as a result of being attached to the wire which was being moved by the aircraft as it moved forward. Almost immediately the chains were picked up bodily and started to thrash around tying themselves in knots and wrapping themselves around the tail of the aircraft. Fortunately the pilot kept his wits about him and managed to stop the aircraft and switch off its engine. As soon as those controlling the exercise realised what had happened the site was cleared of those that had no direct involvement and they returned to normal duty, with plenty to talk about in the meantime.

After making sure that the pilot was OK and uninjured the salvage team set about the task of trying to separate the bits and pieces. First of all it was impossible to move the chains, even by using cranes, because of their weight and bulk and the position and condition of the aircraft, which was eventually cut free, leaving as little with the chains as possible. Once all the bits and pieces were recovered, the whole lot was sent to the dockyard from whence it came for detailed examination. What was left of the aircraft was stored in a hangar and when the enquiry into the cause of the mishap was concluded and had established the cause it was towed away and the serviceable parts were converted into spares.

The reason for the failure was quickly established. The calculations required the anchor cables to be of a certain standard and weight and to be of a certain length. This was all clearly stipulated on the plans and their supporting documentation, but unfortunately, though the length was required to be in yards it was supplied in feet, therefore being only a third of its planned length. The system was put to bed for the time being to allow those concerned to reflect and think again, but I don’t know what was ultimately decided or whether the land arrester system was ever used.

Ernie Coster     February 2014