Aircraft Arresting Gear (AAG) System — stops 6,000–40,000 kg aircraft within 270 m at 3g.

Introduction

On a modern fighter base, everything is designed around speed: high approach velocities, short decision windows, heavy weapon loads and tight sortie cycles. The same parameters that make a fighter effective in combat also make it unforgiving during an abnormal landing or aborted take-off. A fighter touching down long and fast on a wet runway, with anti-skid and brakes working but not enough friction or distance left, has soft ground, perimeter fencing, roads or populated areas beyond the runway lights. At that point, the base either has a dedicated, engineered emergency arresting system, or it is gambling a multi-million-dollar aircraft, a pilot's life and runway availability on luck.

The Aircraft Arresting Gear (AAG) System is that engineered safeguard. Installed at each end of the runway, it uses a high-strength Nylon-66 net, textile purchase tapes and a dual 20T + 40T water-twister energy absorber to safely stop aircraft in the 6,000-40,000 kg class within a controlled run-out up to approximately 270 m, holding peak deceleration to around 3g so the aircraft and pilot can walk away from an otherwise catastrophic overrun.

Arresting Concept — From Overshoot to Controlled Stop

At its core, the AAG converts kinetic energy into heat in a water-glycol absorber, using the net and purchase tapes as the mechanical link. In an emergency, command is given and the two stanchion towers at the runway edges rapidly raise a wide textile net across the over-run. The aircraft enters and is enveloped by this net, which breaks calibrated shear pins and releases from its ground anchors. The net is connected to high-strength purchase tapes that run through sheaves and fairlead tubes to a dual water-twister energy absorber buried at the side of the runway. As the aircraft pulls the net and tapes forward, the absorber spins in a controlled water-glycol bath, converting kinetic energy into heat with a smoothly increasing torque, bringing the aircraft to a controlled stop within the design run-out. The tapes are then rewound, the net is re-rigged, and the system returns to standby.

• Standby mode: net lowered and attached to net anchors; purchase tapes fully wound on the absorber drum; ECS monitoring all subsystem health.
• Emergency deploy: controller triggers deployment from the control hut; stanchion systems raise the net to full arresting height in approximately 3 seconds.
• Engagement: aircraft enters and wraps the net; load rises until ESS shear pins (≈ 2,500 kgf) fail and the net bottom releases, routing load into the purchase tapes.
• Energy transfer & absorption: purchase tapes pay out through sheave assemblies and fairleads, driving the drum on the dual 20T+40T water-twister absorber; the ECS selects 20T, 40T or combined mode via a linear actuator (switching < 5 s).
• Stop and reset: aircraft stops within the design run-out; the tape retrieval system rewinds the tapes, the net is lowered, inspected and re-secured — total turnaround typically 10-15 minutes.

Safety, Maintainability & Operational Advantages

The AAG provides a dedicated, engineered stop for the worst failure cases, not just an incremental improvement in normal operations. Load cells in the tape connector and ESS, along with rpm sensors on the sheaves, give quantifiable data for every arrest event, allowing validation of energy absorption and continuous improvement of procedures. A 10-15 minute reset time keeps the runway and squadron sortie rate intact after an arrest, and materials, seals, coatings and civil design are suited for temperature extremes, humidity, dust, heavy rain and salt-fog conditions common to airbases.

Subsystems are modular — stanchions, absorbers, tape retrieval system, ESS, sheave assemblies, pressure roller assembly — enabling targeted maintenance without full system downtime, and the use of standard industrial components (bearings, gearboxes, motors) simplifies spares management. Scheduled inspections focus on net and purchase-tape condition, wire ropes, sheaves, bearings and seals, energy-absorber fluid health, and civil foundations and anchor points.

Conclusion

The Aircraft Arresting Gear (AAG) System is not a generic ground-support add-on — it is a mission-critical safety asset that stands between a high-speed overrun and a catastrophic loss of aircraft, runway and life. By combining a high-strength textile net, intelligently controlled purchase-tape handling, a dual-stage water-twister energy absorber and a robust control and foundation architecture, the system converts an uncontrolled emergency into a managed, instrumented, repeatable engineering event.