ATL-LIM turns back last night
 

So... seems like this happens to be on a somewhat regular basis. Yesterday afternoon, around an hour after takeoff on DL151 ATL-LIM, the captain informs us that we would be returning to ATL as the "weather radar was no longer functioning". New plane and revised departure time of 23:10 (original departure had been at 17:40). Finally made it into LIM this AM at around 5AM as opposed to just before midnight last night.

All's well that ends well... but in three years of living in Lima I have had three serious mechanicals requiring (one) flight cancellation and two "return to airport once airborne".

Unfortunate to say the least.

I had a delay in LIM due to a malfunctioning radar a few years ago. The overall experience at the airport (from check-in to gate) was not the most pleasant either.

No Lima airport is... functional and not a great deal more. Having said this, the restaurants are now better and the business lounge has been completely refurbished, but it's not a fantastic experience by any stretch of the imagination.

Last Friday we returned to the gate twice after taxiing and ended up with the crew timing out. Flight took off at 9am Saturday and arrived 15 hours late. When you say "new" plane I assume you mean "different", because in my experience the Lima flights use old planes.:(

You haven't been to Mexico City Terminal 1 then. After going through T1 at MEX 2 weeks ago, I thought LIM was luxurious.

This has to do with the age of the planes they fly to South America. Happened to me 3 times in the last couple of years, once in Lima, twice in Sao Paulo. By the way, Peru has a law that requires cash compensation for delayed flights, similar to EU 261. Not sure whether it applies to inbound, but might be worth checking. Last time it netted me around $500.

Had some friends who had their flight ex-LIM recently cancelled because the entire plane's electrical system shorted out (all lights went off during boarding and never came back on).

Apparently it got repaired and they flew back on the same plane about 24 h later. From how they tell the story it sounds like DL proactively refunded their entire D1 fare a few days later before they had a chance to even ask for comp. Not sure if the refund was an actual refund or DL bucks.