Is one-sided thrust reverser deactivation still allowable? While browsing the major accidents in the Aviation Security Network's database, I noticed that a couple of accidents seem to at least be aggravated by one-sided deactivation of thrust reversers. One-sided thrust reverser deactivation seemed to be permissible according to the respective Minimum Equipment Lists, yet the reports indicate that the crews have been caught off guard by the resulting asymmetric thrust after reverser activation during landing.

As some of the mentioned accidents resulted in a high number of fatalities, I wonder if the procedures and requirements regarding thrust reverser deactivation have ever been changed. How common is it for an airliner on a commercial flight to have thrust reversers deactivated asymmetrically nowadays?
Operating with a deactivated thrust reverser is relatively common on normal line ops.

There are normally type specific operating restrictions e.g. full power take-off, no short or narrow runway ops.

On B757/76 there is a clue that you a have a reverser locked out - you can't select it.