US air-drop plan puts premium on hitting targets

THE US air force will be using the 'container delivery system' and a technique known as the 'high velocity air drop' to land aid supplies to Bosnians. The individual bundles weigh up to 2,200lb - 1 ton - with a 26ft parachute. The parachute opens immediately as the bundle leaves the plane.

'It's not correct to characterise it as a free fall,' a US officer said yesterday. 'It's somewhere between floating gently down and free fall. The parachute is to stabilise the bundle so it lands vertically.' The bundles are on plywood palettes, above which there is a honeycomb energy-absorbing device.

The US air force would not comment on estimates of accuracy - that they expected to land the aid packages within 500 metres of the target. 'I'm not going to set ourselves up,' a spokesman said. 'If I say 300 (metres) and they land at 350 then we screwed up. I'm not going to paint us into that corner. We have drop zones in mind and will do the very best we can to put the material in them.'

The number of aircraft to be used is also unknown but each one can carry up to 16 of the 1-ton bundles. Each bundle could contain around 750 ready-to-eat meals. On Saturday night two Hercules aircraft dropped 1 million leaflets over the target zones, warning those on the ground not to approach the falling loads.

One leaflet read: 'US aircraft will be dropping humanitarian aid for all people. Do not fire on US aircraft. Food and medical supplies are intended for all people.' The other read: 'Danger] For your safety let humanitarian aid land before approaching.'

As British and US Hercules crews discovered over Kurdistan, pallets carrying supplies come down fast, even with parachutes. Around nine Kurds died when supplies landed on top of them. The Gulf war allies aimed the supplies several hundred metres away from refugee concentrations so that people would not reach them until the drop was completed.

Even then, they sometimes missed. That was from about 3,500ft above the mountain valley floors - a relatively safe height, out of range of most small-arms fire. The US air force will fly at 10,000 feet over Bosnia to avoid small surface-to-air missiles as well. From 10,000 feet, the supplies will land anywhere in a three- mile long ellipse.

In Bosnia, that is a significant distance. If you are dropping supplies to beleaguered Muslim villages, they could fall to the surrounding Serbs. Those in need might run towards the falling supplies, and be machine-gunned by waiting snipers. A mile is a long way uphill, and longer in Bosnia. The RAF's favoured height is 1,000ft, flying straight and level, at 120 knots. Aircraft at that height will be vulnerable to fire from the ground.

Aircraft flying into Sarajevo use the 'Khe Sanh' method, named after the siege of Khe Sanh in 1968, when the American base was surrounded by the North Vietnamese army and was re-supplied by air. The aircraft fly at 2,000 feet until the 'piano keys' - the black and white markings at the end of the runway - disappear under the nose. Then the crew put the aircraft into a 45-degree dive. But an aircraft flying into an airfield can evade, duck and dive. Not so those doing low-level drops.

The US planes have some very advanced navigation aids, which should make night drops no more difficult than those by day. But weather could be a problem. The 'adverse weather air drop system' should enable the planes to drop through cloud, but it will be difficult getting reliable forecasts of the winds.

Bosnian Serbs, reassured that supplies, and not fuel or arms, will be dropped to all parties, also wish the US air force well. But if the supplies land way off target, kill people or crash into their houses, there will be many choruses of 'I told you so'.

(Photograph omitted)