PLEASE NOTE: The loss or crash of any aircraft outside of the permitted fly zone must be reported via the MAAA Incident Reporting process.

A Guide to Recovering Lost RC Aircraft 

Most of us know the feeling, everything is going well, your beloved aircraft is soaring through the heavens when suddenly it loops, rolls, dives and spins with bits falling off and the motor cuts out while inverted. 

Despite your best efforts frantically waggling the sticks it disappears below the tree line and crashes into the swamp leaving your heart pumping and brain whirling seeking a reasonable excuse not to blame yourself. 

What you do next may greatly increase or decrease the chance of recovering the crashed aircraft. 

The swamp is a large area of dense mangrove forest with a low canopy. It is wet and muddy, reasonably difficult to navigate and line of sight is limited by the dense growth. 

For all these reasons it is difficult to locate a crash site. 

Whilst this guide has been prepared with the swamp in mind, it is of course applicable to the recovery of any lost model aircraft. 

There are a number of techniques that may increase the chance of recovering a crashed aircraft and a number that will decrease that chance. 

Do Not 

  1. Jump up and down on your transmitter and run around with your arms in the air screaming. 
  1. Move from the spot where you last saw the aircraft. 
  1. Rush off in the rough direction toward the crash site. (Unless of course you can see smoke rising, the glimmer of distant flames and hear the crackle of a nice bonfire) 
  1. Begin a search based upon a vague pointy direction of “over there somewhere” 
  1. Wander around in the swamp searching without a plan. You may get lucky but the odds of success are greatly reduced. 

Do This First 

  1. Take a deep breath, remain calm and think of this guide. 
  1. Stay exactly on the spot where you last saw the aircraft. At least note it. 
  1. Identify a distinctive landmark in line with the last sighting and note the aircraft’s direction of travel. A photo will provide a record of that landmark for later reference. 
  1. There may be others who witnessed the crash, so get them to also point and identify the last position seen and direction of travel. 
  1. Try to establish how far away the crash occurred. 
  1. Have a compass app on your mobile phone and establish the magnetic bearing to the last seen position landmark. The more accurate the bearing, the greater the chance of recovery.  A bearing is a straight line or vector between the observer and point of interest. Sight across the top of the compass to the point of interest and read off that line in degrees. That is the bearing.
  1. Leave your transmitter turned on with the throttle switched off. The aircraft’s battery may still be connected. 

Search Using the Magnetic Bearing Only 

  1. Provided the bearing to the last seen position is accurate the crash site will be along that bearing line with an offset adjustment for the aircraft’s direction of travel. This offset adjustment is usually less than 10m. However, the actual offset adjustment applied should no greater than 5m as that is probably the reasonable limit of line-of-sight visibility when searching in the swamp. 
  1. Ideally use a hand bearing compass in preference to your mobile phone compass app. It just works better. 
  1. At the spot where you took the bearing move around 3m-5m in the direction of the offset and with your transmitter turned on proceed along that magnetic bearing course into the swamp. Try to travel along that line as accurately as possible correcting for obstructions. 
  1. Stop every few metres and look around on the ground and up in the canopy. Pulse the aircraft’s engine, waggle the ailerons and check the bearing. 
  1. Continue stopping every few metres until you either find the crash site or extend well beyond the estimated distance to the crash site. 
  1. If you consider that you have travelled beyond the crash site, the best option is to move sideways another 3m-5m in the direction of the offset and return along the reciprocal bearing, stopping every few metres as before. 
  1. If there is more than one searcher available, set off around 5m-6m apart and follow the bearing keeping a parallel course and work as above. 

Search Using a Drone 

  1. An eye in the sky will improve the chance of recovery and is worth a try. However, this may not be all that successful over the swamp as the aircraft may be on the ground screened by the canopy. If the aircraft is resting on top of the canopy, it will probably be visible from the air. 
  1.  Use the bearing line as above and search up and down that line and progressively to each side. 

Using Your Transmitter as a Radio Direction Finder 

  1. If the aircraft is fitted with a receiver that provides telemetry and the battery is still connected, when in range, the receiver will communicate with the transmitter providing useful information that may assist the search. For example. A variometer providing altitude may indicate whether the aircraft is on the ground or in the canopy. Signal quality displayed as RSSI, decibels or a percentage can be used to determine the direction to the crash site. 
  1. When on the ground the signal quality between the transmitter and receiver is greatly reduced so that following a crash there may be no telemetry received. Do not assume that the aircraft’s battery has become disconnected, the receiver may just be beyond signal range. 
  1. The aerial on the transmitter is most effective when it is at 90 degrees or side on to the aircraft and least effective when pointed to or in-line with the aircraft. This property allows the transmitter to be used as a radio direction finder and seems to works best when both are just in range and less well when close up. 
  1. Depending upon the transmitter, access the telemetry page that displays signal quality. When searching as in section 3 above, at each stop, move the transmitter from side to side and check to see if a signal is being received. If the aircraft’s battery is still connected and you are approaching the crash site, signal data will appear on screen indicating that you are moving closer. 
  1. Once a signal is detected, stand on the spot, point the aerial away from you and hold the transmitter close to your body. Slowly turn through 360 degrees noting the signal strength. Ideally there should be two signal peaks 180 degrees apart and two signal lows at 90 degrees to the peaks and 180 degrees apart. The weak signals will indicate that the aerial is either pointing to or away from the crash site and the strongest signal will indicate that the aerial is at right angles to the crash site. Whilst this data will indicate the line of direction to the crash site, the problem is that the crash site could be on that weak signal line in either direction 180 degrees apart. To determine the correct direction on that weak line, hold the transmitter close to your body check both weak signal strengths 180 degrees apart. Your body will blanket and reduce the signal when it is between the crash site and the aerial. Therefore, the stronger signal of the two will indicate the direction to the crash site. Move in the that direction and continue to check every few metres. Pulse the motor, waggle the ailerons at each stop until you are close enough to hear something. 
  2. Whilst that all sounds great, in reality the process is a bit more hit and miss, but it does work and will improve the chance of recovery. The good thing is, that if a signal is received, the crash site will probably be within 50 metres or less and as you move closer the signal will become stronger and conversely weaker as you move away. Once within signal range, use the range test feature to reduce signal strength, which may further assist you homing in to the crash site.  

Other Considerations 

  1. If you have a telemetry receiver your transmitter should be set up to receive the full range of data available. With the receiver powered on, in your transmitter settings go to Telemetry and select Auto-Configure. After a few seconds the available data fields will fill in. More data is better than less. 
  1. Some newer transmitters are fitted with diversified aerial systems. That is, not only is the transmitter fitted with the external aerial you can see, but also has an internal aerial often inside the handle or parallel with it at 90 degrees to the external aerial so that a diversified (more reliable) signal is transmitted and received. This is a similar set up to the twin aerials on some receivers. This causes a problem with radio direction finding but either aerial can be partially screened with your hand and if a difference in signal strength can be observed when rotating through 360 degrees useful information is available to you for interpretation. Again, worse-case scenario is that any signal that is getting stronger indicates you are moving towards the crash site and any signal that is getting weaker indicates you are moving away. 
  1. Bottom line is, take your transmitter with you switched on when you go searching. 

Aircraft Crash Beepers 

  1. The chances of recovering a crashed aircraft are greatly improved if the aircraft is fitted with a Crash Beeper or Finder. 
  1. There are a number of Beeper types available with different features enabling a range of tasks. This section only covers Crash Beepers or Finders. 
  1. The simplest of these devices are small, light and cost around $10.00 each. They consist of a small circuit board with integrated beeper, LED and tiny LiPo back-up battery. They have positive and negative connecting wires that need to be connected to the receiver power supply from the ESC or a spare channel port on the receiver. When the flight battery is connected in the aircraft, the back-up battery charges. When the flight battery is disconnected, the loss of power is detected by the Beeper and it starts to beep and flash until either the battery is discharged or the device is reset via a small button on the device. Typically, when fully charged they will continue to operate for several hours. 
  1. By fitting a Crash Beeper or Finder the chances of finding a crashed aircraft where the battery has disconnected are greatly improved. 
  1. These devices are also available with an additional signal connection that allows the beeper to be switched on and off remotely at the transmitter via a dedicated channel connected to a relay or flight control board and allocated switch on the transmitter. Provided the channel condition can be programmed for fail-safe to switch on, then the beeper can also be activated both when the flight battery is connected via a switch when in range, and automatically on loss of signal, fail-safe condition, and automatically when the flight battery is disconnected.  Technology is a wonderful thing. 

Conclusion 

  1. If you do crash into the swamp, by following this guide there is a reasonable chance that you will find the crash site and recover your aircraft. 
  1. Fly with a telemetry receiver and the odds are improved. 
  1. Fly with a telemetry receiver and crash beeper and the odds are improved even further. 
  1. Remember, the best way to recovery a crashed aircraft is not to crash in the first place. Before flying check the airframe, servos and linkages, hinges, operation of all surfaces, CG, range test and connection to brain. 

Have Fun and Best of Luck.