THE empire strikes back, and how. In an aggressive and unusual—at least going by the standards of lethargic public sector units—marketing move, the state-owned Indian Airlines last fortnight announced the introduction of metro shuttle flights or flights every hour between Delhi and Mumbai, the sector which has the highest passenger load factor, beginning March 29. The experiment, if successful, is to be extended to other popular sectors the airline services—Mumbai-Bangalore, Mumbai-Chennai and Delhi-Bangalore.