By Aditya Mandrekar
With news that Iran may have downed one of the United States’ most secret spy-planes — an RQ-170 Sentinel built Lockheed-Martin — the internet has been abuzz with claims, counter-claims and outright denials that it could have happened. Now that Iran has officially released footage of the UAV in their possession – one that does resemble the ‘Beast of Kandahar’ from the few photos available – speculation has turned to precisely why the UAV is in Iranian hands.
- The UAV may be a blended wing design, but there are no obvious “stealth” characteristics. A meshed air intake is not enough to make an aircraft low-observable and could simply be there to prevent foreign object damage (FOD). The control surfaces too do not have any serrated (jagged) edges that are needed to spread radio wave reflections; neither do various panels on the aircraft.
- Amusingly, the aircraft is placed on a plinth instead of its own landing gear. Which means either the gear stayed retracted or was torn off on landing, either pointing to signs that it wasn’t made to land in a controlled manner.
The most exotic claim is of course ‘it was hacked’. This is also the one least likely to be true and ironically the one explanation that the speculators seem to long for. The possibility of a spy plane flying with a datalink continuously active is quite low. There are many reasons for this, but security (exposing the communication channel for long durations) and power consumption (to power the receiver and, in some cases, a transmitter for two-way communication) are chief concerns. UAVs obviously can be fed course correction updates in real time if sudden changes are necessary. But these will be brief and short transmissions that will be irregular and hard to break into – encryption levels are beyond the average supercomputer’s power to break in reasonable time, not to mention the possibility of passcodes changing every mission.
This leaves open a possibility where the Iranians could have mimicked a remote command – but then again they would have to have the same datalink equipment and encryption methods as the CIA and an ability to transmit it to the exact spot in the sky they want to, and at the right time. And even if this is the case, the moment an operator noticed the UAV going off course, the CIA would have not hesitated to countermand its last commands and restore communication, this time either on different frequencies or with different codes.
Next, there is speculation that the UAV was “jammed”. The response to this is on two levels: What was jammed? And, so what?
As mentioned before, the average spy craft will not always have its receiver running apart from intelligence gathering purposes. So the probability that its control could be “jammed” is insignificant. What is possible, though, is that the GPS receiver(s) on the Sentinel could be jammed with the attempt to deny navigational aid. This is unlikely too because for one, it means flooding the UAV at its operating altitude with enough radio energy on ALL channels (including US DoD military GPS frequencies) from above (since the antennae are on the upper surface) to attempt to disable satellite receivers.
And even if GPS data was lost… so what? Between inertial sensors, magnetic compasses and radio homing beacons, UAVs are not 100% reliant on GPS for navigation. In fact, autonomous flight control software is written with explicit instructions built-in that unmanned aircraft facing loss of critical sensors have to head to a particular location or direction where recovery can be attempted, either through re-establishing system integrity or getting it to land in a controlled location.
Then there is the initial claim by Iran that the Sentinel was shot down. This seems unlikely to me; there is no sign of external damage on the upper body, and more importantly, none on the leading and trailing edges of the aircraft. This leads me to believe that there was no contact between AAA rounds and the drone, let alone a missile proximity explosion.
The more one looks at it, the simplest answer seems to fit the data best – equipment failure. As unglamorous as it sounds, loss of propulsion is the most likely reason for the loss of the Sentinel. Whether an engine failure or a fuel leak, it is most likely that the aircraft lost power and with it, any hope of making it back. The Iraq-Iran-Afghanistan region is one of the least forgiving environments of operation, and it is not hard to imagine dust, sand and gravel causing lasting damage.
There is also the likelihood that power to the control surfaces was lost, but it is hard to believe that the Sentinel does not have at least dual redundant controls. However, the aircraft is smaller than previously imagined, so it may be that the source of electrical power is single. If this is a battery, it could be simply battery failure. If the power was delivered from a turbine-driven alternator, then it is even more evident that loss of engine power would mean a loss of electrical power.
ADITYA MANDREKAR is an electrical and avionic systems engineer who currently writes embedded software for an electronics company in the UK.
This post reflects the independent views of the contributing writer.