I have been asked to fly around a new construction site, they want me to fly under quite a long concrete bridge, my question is, will the Inspire loose it GPS and then initiate return to home or if I am very close to it will it just keep flying due to the close distance of the transmitter?

Whis would be helpful if ever flying from outside to and internal structure.

Thanks everyone in advance

It is certainly possible especially if it is re-enforced (highly likely). Large metallic objects are your enemy.
It is more likely however to affect your compass causing a slight or sudden yaw in the aircraft's direction due to the changes in magnetic field.

Losing GPS will not make your aircraft return to home though. Only losing control signal or pushing the RTH button on the transmitter. Instead, it will force is into P-ATTI mode meaning you will have to apply your own inputs to the controls to keep a stable hover. The visual position system in the Inspire should help if you are close to the ground though.

I have flown through a few sites myself however I prefer to fly in ATTI mode as the loss of GPS can cause the camera to twich.
My advice is to perform a site assessment, map out the flight path and make detailed notes of objects that are above and around that might obscure the sky and absorb the GPS signal or cause magnetic issues.
It helps to have an iPhone or Compass to see the changes in the magnetic field as you check. Keep close to the aircraft and have a good clear view of the flight path as you fly.
Do not do it FPV as you will not be able to respond to the potential changes in the aircraft fast enough.

great help, thank you very much appreciate you taking the time to write it.

Dave
SkyCam Media Aerial video andAerial Photography

I flew under a relatively long and large concrete bridge about a month ago and had zero issues other than my nerves. lol  Also flew under a smaller low bridge in the mountains at a lake while skimming the water and a few months ago and had zero issues. I would probably say your relatively safe but I would always keep your finger ready to change over to atti mode if necessary.

One issue I see is that if you loose line of sight or signal and are under the bridge.   The inspire will issue a return to home and will rise right into the bridge.    I would stand in a place where I constantly see the inspire and fly under with an un-obstructed view.  Should be ok.  but if it's metal and you are on the bridge or off to the side where you loose visual, it might loose signal.   Probably not but er on the side of caution

I fly over and under 2 bridges in this video, one is concrete and the other steel.
I had no issues on either. The bridge is right around the 8:00 mark.
Have fun