What if you lose GPS flying and no line of sight to return home?

MiniPalourde · Mar 11, 2018

kakao said:
Are you 100% sure about that?

/

He's wrong. The arrow won't point at you if you lose GPS but it has nothing to do with the compass or new sites.

laurens23 · Mar 12, 2018

there are 3 important connections: GPS, RC and FPV(phone).

Below the scenarios:

Lost FPV --> available GPS + RC --> action: RTH button, or when in VLOS navigate visually, or when BVLOS navigate by decreasing distance number on the RC remote.

Lost GPS --> available RC + FPV --> action: navigate home based on landmarks, or decreasing distance number on RC remote. Be careful because you will be in Atti mode.

Lost RC + FPV --> available GPS --> action: RTH (automatically after 3 sec of no RC signal)

Lost GPS + FPV --> available RC --> action: when in VLOS navigate visually when BVLOS (auto)land and go pick up the drone.

Lost GPS + RC + FPV --> available none --> action: depending on settings it might auto-land on the spot, or fly until critical low battery. Due to no GPS it will drift downwind.

Notes:
[1] If you lose RC you also lose FPV.
[2] Listening to the sound of the drone can help navigating back.
[3] compass and map might help navigating back, but careful to trust compass when there are obviously already connection/interference issues.
[4] Drop from sky or flyaway are never the cause of a simple loss of signal. They are either pilot error or another malfunction in the RC, Drone, or phone.

off topic:

Mad Mavic said:
Picking out a landmark is excellent advice MavicCF. As a general aviation pilot, we call that seat of the pants flying. Not sure why but it simply means the pilot is flying without instruments,

this is not true:

seat of the pants flying has a clear origin. Flying "by the feeling of one's *** (pants) in the seat of the plane". It dates from the Army Air Force of World War II. It means operating (NOT NAVIGATING) an aircraft (and hence any very complicated affair) by instinct and feeling rather than by instruments or other assistance.

Pilotage is navigating based on landmarks.

Dead reckoning is navigation based on mathematical calculations of speed, time, distance, and direction.

Mad Mavic · Mar 12, 2018

laurens23 said:
there are 3 important connections: GPS, RC and FPV(phone).

Below the scenarios:

Lost FPV --> available GPS + RC --> action: RTH button, or when in VLOS navigate visually, or when BVLOS navigate by decreasing distance number on the RC remote.

Lost GPS --> available RC + FPV --> action: navigate home based on landmarks, or decreasing distance number on RC remote. Be careful because you will be in Atti mode.

Lost RC + FPV --> available GPS --> action: RTH (automatically after 3 sec of no RC signal)

Lost GPS + FPV --> available RC --> action: when in VLOS navigate visually when BVLOS use decreasing distance number in RC to get back, careful you'll be in Atti mode.

Lost GPS + RC + FPV --> available none --> action: depending on settings it might auto-land on the spot, or fly until critical low battery. Due to no GPS it will drift downwind.

Notes:
[1] If you lose RC you also lose FPV.
[2] Listening to the sound of the drone can help navigating back.
[3] compass and map might help navigating back, but careful to trust compass when there are obviously already connection/interference issues.
[4] Drop from sky or flyaway are never the cause of a simple loss of signal. They are either pilot error or another malfunction in the RC, Drone, or phone.

off topic:

this is not true:

seat of the pants flying has a clear origin. Flying "by the feeling of one's *** (pants) in the seat of the plane". It dates from the Army Air Force of World War II. It means operating (NOT NAVIGATING) an aircraft (and hence any very complicated affair) by instinct and feeling rather than by instruments or other assistance.

Pilotage is navigating based on landmarks.

Dead reckoning is navigation based on mathematical calculations of speed, time, distance, and direction.

see: Douglas Corrigan 1938.

I’ve heard this term used in lecture as well as during maveuvers so perhaps the meaning has evolved slightly . It was actually coined by a newspaper reporter.

The common definition : “To pilot an aircraft without the aid of instruments and without a flight plan, using only instinct, visual observation, and practical judgment.” Seems to relay more closely to my previous insertion regarding the importance of landmarks.

What ever the case, should you lose all aids to navigation, I’m guessing it’s time to buy a new drone. I read something about it’s ability to teturn via bread crumb but I’m sure GPS is needed.

I’ve been in IFR conditions and managed to get myself turned around using turn and bank indicator and a clock.

I suppose if you were paying attention to your heading prior to a total loss of intriments, and knew the time required to turn 360 degrees, as well as max rate if decent, the perhaps you could attempt a turn to heading, drop to a safe altitude, and hope for the best.

For example; if it took 4 seconds to turn 360 degrees, and 5 seconds to defend 100 feet. Let’s say you were flying north at a heading of 15 degrees. And this heading was 165 degrees off the vector to home of 180 degrees, and 200 feet above SRTH altitude. Right turn for 1.75 seconds and decend for 10 seconds. Assuming you are able to calculate you true ground speed given the wind direction, It would be an absolute miracle if you hit the mark in high wind conditions. In dead calm, not a problem

Logger · Mar 12, 2018

laurens23 said:
....

Lost GPS + FPV --> available RC --> action: when in VLOS navigate visually when BVLOS use decreasing distance number in RC to get back, careful you'll be in Atti mode.

Without GPS how do you propose that the RC would be able to calculate and indicate a distance number? If it simply had dropped from GPS Navi to Atti mode I would buy that. But IMO Lost GPS fix = no distance readout.

Peter 101 · Mar 12, 2018

I lost gps just after take off was at about 5 mtrs up . Itjust stopped would not return to home and controller wouldn’t work . It stayed there for 10 min . I was re starting controller and app . Only after gps came back could I land.
I’ve sent it away to get the gps replaced as it was not connecting properly.

SkyIScrape · Mar 28, 2018

Hypothetical not hypocritical. But as I was just spelling “hypothetical” it auto-corrected to “hypocritical”. So I’ll give you the benefit of doubt. Hypocritical seems to be a very common word these days so I can see why the algorithm is such.

laurens23 · Mar 29, 2018

Logger said:
Without GPS how do you propose that the RC would be able to calculate and indicate a distance number? If it simply had dropped from GPS Navi to Atti mode I would buy that. But IMO Lost GPS fix = no distance readout.

thanks, updated my post

Dragonfly · Jun 18, 2018

MiniPalourde said:
He's wrong. The arrow won't point at you if you lose GPS but it has nothing to do with the compass or new sites.

Sorry you are wrong, if you loose GPS and Mavic goes into Opti/atti mode the compass still works and still displays and shows Mavics orientation on your device screen.
You can use this to orient the Mavic back at your direction then push full stick forward. Even if the main GPS wire disconnect or breaks, Mavic will switch to its second compass witch is mounted in front of craft. Sure it won't know where it is but when it looses GPS it will still show red arrow (due to compass and last know position on device map) and if you have GPS on your device, your position, so just rotate craft to point Arrow at you and fly home.

AleksandrOrlov · Jun 19, 2018

Scottd9000 said:
I was flying over a large lake at sunrise and my iPad died due to cold. It was hovering way out and right in the sun. Basically had to just trial and error using sound to tell if it was getting closer. Coming from an original Phantom home lock was nice to have on the controller.

Or just hit the RTH on the RC