Hi everyone, I was flying in the middle of Sydney city today. We were surrounded by tall buildings and flying above some buildings around 30m high. GPS signal was very sketchy (one second was connected to 9 sats then the next was connected to 4) so didn't use position mode. Shortly into the first flight just as I got above the tallest building on the block we were filming, the orientation lights started flashing. I immediately tried to descend and land, but the ALTA was unresponsive. Then it lurched in our direction uncommanded for about a second. Then I regained control and landed. In the next few flights I was super tentative and nervous, but we didn't encounter any problems. I just reviewed the flight logs and it appears there was a radio LOS incident occurring on both receivers precisely at the same time. I have two questions. 1. Does anyone have any idea what could have caused this? This has never happened before in my experience flying the ALTA. I thought it may have been something on the roof of the building that interfered with the signal? 2. The ALTA looked as if it initiated a return to home and then when the signal was regained I took control and returned it myself. My question is in this instance, when GPS signal was highly unreliable, would the ALTA have found its way home OK if I hadn't been able to regain control? Bit of a scary one. especially considering all the buildings around. Thankfully we had control of the street below, so if something worse had happened it would have most likely just been damaged property, not damaged people, but still it got the blood flowing pretty fast, and didn't make the following flights particularly pleasurable.