FOLLOWING Northwest's change of heart on its standby US air pass, Delta Air Lines (0800 414767) has also given its pass a reprieve. It has announced that it will be offering a Standby Travel Voucher Program until 31 March next year - but with a dollars 50 price increase. The price for its 30-day voucher is dollars 549 (pounds 378), while the 60-day voucher costs dollars 899 (pounds 620).