[jimworcs]

Many people on this site might faint, but I am going to defend Delta. It is unrealistic to expect airlines to be able to route you without disruption when an extraordinary natural event, such as a volcano, occurs. Somethings are just outwith the control of airlines. I have a friend who has been stranded in Australia for over 2 weeks, even though flights resumed more than a week ago.

The fact that they were unable to accommodate you on a direct flight is not unreasonable. When flights resume, these aircraft already have people booked on them. Therefore the number of available seats is limited. In order to reduce the time that you remained stranded, it is reasonable and fair for you to be routed via Atlanta and to an alternative London airport.

If your journey originated in Europe and you travelled to the US on a return ticket, I have some good news for you. Under European Law (EU 261) Delta are required by law to reimburse you for your reasonable accommodation costs in New York and for the costs of up to 3 meals per day. This is a legal obligation on the airline in the event of a flight cancellation, irrespective of the cause. All the major airlines have accepted their liabilities in this regard, even Ryanair (who initially announced they would not pay and promised to take it to court, but rapidly backtracked when they realised they would have a huge class action law suit on them).

So you may be entitled to some redress. If your journey was originating in the US, I fear you may be entitled to nothing. There is less protection for travellers under US law than under EU law. However, you may be able to claim the costs associated with travelling from Gatwick to Heathrow. That is probably not much more than $30 I would imagine.