It will introduce four flights on weekdays and two a day on weekends between Cardiff and London City Airport .
The 1886 rail tunnel will shut between September 12 and October 21 for electrification work as part of a £2.8billion programme to speed up journeys from Wales to London.
Flybe’s Vincent Hodder said: “Flybe champions regional air travel and we hope these rescue flights will help alleviate the travel woes of the thousands of passengers displaced by the loss of the region’s direct rail services.”
Cardiff Airport MD Debra Barber said: “This is really good news for Wales. It’s fantastic to see the Flybe response.
"The airline’s offer to step in and create alternative options for Welsh business and leisure passengers to travel to London by air from Cardiff at such short notice, is further evidence of the confidence they feel about growing their flights linking Wales to key British, Irish and European cities.”
Work has already been carried out to prepare the 130-year-old tunnel for closure with four tonnes of soot removed from the tunnel walls and 7,000 holes drilled into the roof. A conductor rail will be installed to provide power.
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