This page shows the air skills only the A-Gear has.
Ground Accelerator: 
Level 1
Level required: 12
Purchasing price: 8000 SPI
SP cost: 4 SP/sec
Movement speed: +100%
Level 2
Level required: 60
Purchasing price: 30000 SPI
SP cost: 4 SP/sec
Movement speed: +150%
Level 3
Level required: 90
Purchasing price: 524000 SPI
SP cost: 4 SP/sec
Movement speed: +200%