Business travellers flying from Heathrow will not be able to cut it as fine as they used to after the airport's Terminal Five opens on Tuesday.

They will have to pass through a new security check and will be turned back if they fail to get there at least 35 minutes before departure.

The extra check should help to avert problems that cause delays, says British Airways.

For example, it will alert staff at the departure gate that a passenger who has checked in online has arrived at the airport. At present they are often unaware until the last minute.

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BA, T5's sole tenant, is clearly making a virtue of necessity. Domestic and international customers, separated up to now, will be able to mingle before boarding.

So the airline needs to ensure they will not be able to swap identities.

As well as reading their boarding passes, equipment at the new checkpoint will photograph and take a four-finger biometric record of domestic travellers.

"The information will be destroyed after staff at the gate have ensured passengers are who they say they are," says a BA spokesman. "The new check is to their overall benefit because it will result in fewer delays."

Cutting down delays is the sine qua non of the £4.3bn ($8.5bn) terminal.

Every inch of it is designed to restore Heathrow's severely-damaged reputation by ensuring that passengers are processed more efficiently, more flights leave on time and baggage turns up according to plan.

BA promises that, for the vast majority of travellers, progress from check-in to the departure lounge will take no more than 10 minutes.

The terminal will be able to handle 27m passengers a year from the outset and an extra 3m from 2011 when the second of two departure gate satellites opens.

That is nearly half the annual 68m currently passing through Heathrow's four existing terminals, which were designed to handle 45m. T5 will function on two main floors - arrivals at ground level and departure above.

"Currently about 60 per cent of our passengers check in online or at self-service kiosks," the BA spokesman says.

"T5 will get that up to 80 per cent. There will be 96 kiosks and over 90 fast bag drop desks.

"We've tried to make it much more intuitive. Sometimes in Terminal One you have no idea where you need to queue. When it's busy you are not sure whether you are waiting for our desk or someone else's."

Passengers with problems to be resolved, including those that require returning to a ticket counter, will be dealt with at another line of desks, beyond the fast bag drop.

"Usually, baggage check-in is at the back wall of the departure area because that's where the baggage system starts," says the BA spokesman. "In T5 it's different. Instead of turning back on themselves when they have dropped their bags, they will carry on straight ahead. They need never turn through 180 degrees."

Even when the number of passengers using the terminal has reached its maximum, there will still be spare baggage capacity, BA claims, and while passengers and travel managers still question whether gremlins may sneak in, the airline has been working to sure they are excluded.

It has been testing the system by pushing through up to 12,000 bags a day.

"Bar codes on bag tags will be scanned every few seconds so that we can identify those which need to be speeded up because of an imminent departure," says the spokesman.

"We will also be able to locate bags more quickly if they need to be offloaded. At present it's quite a cumbersome system.

"We aim to get bags to the carousel before the passenger arrives there."

The fact that 90 per cent of BA's transfer passengers will switch flights without changing terminals should also lead to fewer hold-ups.

It is not just the internal design of T5 that should reduce irritations.

Frequent travellers complain that one of the greatest of all frustrations is to land at Heathrow only to crawl across the airport and then sit on the tarmac while the crew waits for a parking stand to become available.

But T5's location means aircraft will not have to taxi across runways after touching down.

And they will no longer have to wait for another aircraft to clear the parking cul-de-sacs that cause delays at existing terminals.

Passengers with time to kill, perhaps before boarding long-haul flights from Satellite building B - linked to the main building by driverless trains running every 90 seconds - will be able to do so in one of five lounges, depending on their ticket type or frequent flyer scheme status.

They will provide 25 per cent more capacity than those operated by the airline in Terminals One and Four combined. Four will be in the main departure area and one in the satellite.

There will also be an arrivals lounge.

Retail outlets will include Mappin & Webb, Tiffany, Dior, Gucci, Prada and Bulgari.

Travellers hit by delays that clever design can do nothing to prevent, such as those caused by weather or air traffic congestion, will be able to soothe frayed tempers at a travel spa, offering treatments including facials and massages - or dine at one of about two dozen eateries such as Carluccio's (Italian) and Plane Food, Gordon Ramsay's 180-seat restaurant.

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Who flies from which terminal?

A huge shake-up will accompany the opening of Terminal Five, with 54 airlines switching terminals in eight phases.

All but 30 per cent of British Airways' services will move into the new building as soon as it opens.

These include all domestic and international short-haul flights now using Terminal One (T1) except those to Madrid, Lisbon, Nice and Helsinki, which will operate from T3 starting on September 17.

Long-haul services using T1, short-haul flights from T4 and Miami services - currently using T3 - will also move to T5 at its inception.

Algiers flights, currently from Gatwick, will operate from T5 from March 30.

On the same date, BA's Houston flights will move temporarily to T4, shifting to T5 a month later.

All other inter-continental services will move from T4 to T5 at the end of April - except those operated by either BA or Qantas under joint service agreements to Bangkok, Singapore and Sydney, which will move to T3 early next year.

BA's airline partners in the Oneworld alliance will be based in T3. American Airlines, Cathay Pacific, Japan Airlines and Royal Jordanian are there already.

American will transfer its Raleigh-Durham services and one of its Dallas-Fort Worth flights there with departures starting on March 29.

Finnair and Iberia will operate there from September 17 and Qantas from early next year.

Star Alliance airlines will use T1.

United Airlines and Air New Zealand will operate there from June 10. Carriers in the Skyteam alliance will operate from T4.

They include Delta (NYSE: DAL - News) , Continental (NYSE: CAL - News) and Northwest (NASDAQ: NWAC - News) , which will all launch new services from Heathrow this spring as a result of the recent US-UK open skies agreement.

One member, KLM, already uses the terminal, while five others - France, Alitalia, Czech Airlines, Aeroflot and Kenya Airways - will move there next February.

Meanwhile Virgin Atlantic has confirmed it will stay in T3 but Jet Airways, Gulf Air and Malaysian Airways are scheduled to move from there to T4 in September.