Imagine you paid a huge air fare & suddenly, your airline tells you that you will have to half journey in buses. This has been the recent case when SpiceJet actually cancelled its flight from Mumbai to Darbhanga & instead used buses. For more details, read full article.
SpiceJet or Spice Buses!!
SpiceJet is an Indian Low Cost Carrier, which is known in the avgeek community for being the one with highest Passenger Load Factor & inconsistent service. The airline connects Darbhanga with Delhi, Mumbai and Bengaluru. It operates daily flights between Mumbai & Darbhanga. But on 18 & 19th November, something interesting happened. The airline prematurely cancelled its flight between Mumbai & Darbhanga.
It rescheduled passengers on flight from Mumbai to Patna. For your information, Patna & Darbhanga are 141 kilometres away from each other & it easily takes 3-4 hrs to cover this distance with bus. The passengers travelled by air from Mumbai to Patna & were then ferried to Darbhanga via buses. The passengers travelling from Mumbai to Darbhanga were expected to land on 03:55 PM but due to this mishap, they reached 8 hours later on 12:00 AM.

The same thing was done for outbound flight. Passengers were ferried from Darbhanga to Patna in buses & were rescheduled on flight from Patna to Mumbai.
Why?
The exact reason for this is unknown. There is one possibility that Darbhanga is a VFR airport, and hence, the airline was not able to land because of low visibility. But it is not correct. On both of these days, weather in Darbhanga was shiny. Add to that, SpiceJet’s operations from Delhi & Bengaluru to Darbhanga were seamless. The flight from Delhi landed just around time Mumbai flight lands. So, obviously, weather conditions were not the reason.
There may be a chance that SpiceJet would have deployed its Boeing 737 for additional World Cup flights. So, because of no aircraft available, the airline took this step.

One more argument is why not schedule them via Delhi? SpiceJet generally operates with good Passenger Load Factor & hence, it may be possible that there were not enough seats available for all the passengers in the aircraft flying from Delhi to Darbhanga.
Source : Prabhat Khabar