HAPI light，its full name is Heliport Approach Path Indicators. HAPI is CHAPI (CRAMP'S HELIPAD APPROACH PATH INDICATOR).

The ‘C’ in CHAPI stands for ‘Cramp’, the name of person who invented the hapi light system 40 years ago to help train pilots returning from Vietnam. Dave Cramp was a training captain for Bristow Helicopters in Dubai, “I was tasked with training ex-Vietnam pilots we had just employed. They were all very experienced pilots, but they had problems flying in a civilian environment where they weren’t being fired at. My job was to ‘civilianize’ them. The big problem was getting them to fly steep approaches instead of coming in very low with a big flare just before ‘crashing’ on to the helipad. I needed a way to get them to see and adopt a 6-degree slope. Hence the CHAPI. It was originally made of wood with a slot at the front. My next prototype was constructed out of a plastic water container. I used this for 3 years before a company in Rugby, UK offered to further develop the device. The first commercial sale was to Aberdeen Airport in Scotland in 1982 and it is still being used there today.”