ATU Overview

An Additional Telemetry Unit or ATU is an electronic module that collects fire attack data and sends this information to the USFS via an Automated Flight Follower (AFF).
The following is a typical process of an ATU based upon USFS requirements:
  • An ATU pin must be grounded thru the belly disconnect when a bucket is connected. This keeps the ATU from sending non fire attack data such as long line loads. The ATU will not startup unless this pin is grounded. Typically, connector P2 pin C.
  • The ATU waits until a significant load is applied (our ATU has a 100 gallon threshold) before the ATU begins to measure the water for a FILL event .
  • After the water FILL in the bucket (or tank) is stable (not changing more than 40 gallons for 5 seconds) and is more than 100 gallons the ATU send the AFF a serial message: FILL nnnn gallons. This message is then sent to the AFF. The AFF adds GPS information and then sends this data to the AFF webportal and also the USFS ground station.
  • The pilot OPENs the bucket gate (or tank door). The ATU sends the AFF a serial message: Bucket/Tank OPEN. This message is then sent to the AFF. The AFF adds GPS information and then sends this data to the AFF webportal and also the USFS ground station. The water quantity (W1) is also measured and stored before the OPEN is recieved.
  • The ATU waits until the water quanity has stopped decreasing and then records the water quantity W2. The ATU determines the amount of water dropped (W1-W2). The ATU sends the AFF a serial message: DROPPED nnnn gallons. This message is then sent to the AFF. The AFF adds GPS information and then sends this data to the AFF webportal and also the USFS ground station.
  • The ATU waits until the pilot releases the bucket gate (or tank door). The ATU sends the AFF a serial message: Bucket/Tank CLOSED. This message is then sent to the AFF. The AFF adds GPS information and then sends this data to the AFF webportal and also the USFS ground station.
  • If the water quantity is greater than 100 gallons (i.e partial drop), the ATU will wait for the pilot to OPEN the bucket gate (or tank door) (see step 4 above). If the water quantity is less than 100 gallons the process is repeated (see step 2 above).