When easyJet started operating years ago, it raised tons of questions amongst the potential customers. How can they be so cheap ? Will they survive the market ? Will the other survive the market ? Are they on time ?... but the main one certainly was "Are they as safe as a classical company ?"
The answer to this one is definetly yes. They certainly had some incidents, but no crash for the time being. Ryanair also has a virginal crash record for the time being.
The low cost airline is sustained by three pillars:
1) Modern fleet and single type of aircraft
2) Reduced services to passengers
3) High added value at minimal cost
Let's go through them all...
Fleet management
At initial startup, easyJet was operating with boeing 737's only, and now they operate a fleet made of Airbus 319's only. There are multiple advantages to a single type fleet. First, you need less pilots. In a classical company operating many type of aircrafts, you need reserve pilots for each and every types. In a single type fleet, you need reserve pilots only for one type, so you can operate the same number of aircrafts with less pilots, and then you can offer them very attractive salaries.
It is not unusual to have slightly higher salaries by low-costs companies than in classical ones for flight crew (pilots). Ground handling crew is another story...
The same applies to maintenance spare parts and mechanics. Airplane mechanics are licensed for a certain number of aicraft types, but not all. So operating a single type of aircraft makes the maintenance less complex to manage, and you need spare parts for this single type only.
The drawback of the single type fleet is the reduction of possible operations. Classical companies have various types for various operations (short flight, trans-oceanic, ...). So the low-costs as we know them from the last years will not operate trans-oceanic flight.
Reduced service to passengers
The most widely known reduction in services offered to passengers on low-cost airlines is the fact that you have to pay for your sandwich / croissant / coffee if you want some. But this is by far not the sole reduction.
On low-cost airlines, you have no customers desk. Some of them are even no longer accepting ticket-ordering by phone, but only over the internet.
Bookings can usually not be modified, or at very high prices. And one of the most important thing making a low cost easier and cheaper to operate is the absence of alliances with other companies. When you travel with a classical company and that the flight is cancelled, the company will try to put you on a flight from a different company, or a later flight. Can you imagine the kind of commercial agreement and operational issues raised by such a possiblity ? A low-cost company will never offer that. Your flight is cancelled ? Take the next one, or buy a new ticket by a concurent.
Welcome to Paris Beauvais airport
An other way of reducing passenger service is to land in less expensive airports, which means a bit farther away, but also sometimes quicker to go through. The transfer to terminal / customs / immigration process in Luton is much shorter than in Heathrow, especially if you land just after a 747 of Chinese people.
The risk with this strategy of smaller airports it to fall in extreme cases. From my point of view, it's ok to say that Gatwick is an airport in London. Saying the same about Luton is already ... different. The one hour bus trip is quite long, especially if the previous flight did last for 1h15 !
The extreme example of this is a company selling tickets to Paris Beauvais airport. For those of you not knowing where Beauvais is, 66 kilometers north of Paris. The bus transfer lasts for 90 minutes when traffic is ok. As a comparison, Luton is "only" 45 kilometers north of London.
Knowing that the average benefit per passenger and per leg is 2 english pounds, any person paying for speedy boarding will bring the company double benefit ! How easy is that ?
Losing a plane in a crash is always a human tragedy at first. No one discusses that. But it also has financial and economical impact on the airline. Many classical airlines, including the most prestigious ones (AirFrance, Swissair, United, Lufthansa...) lost planes. They all survived this tragedy, with more or less consequences.
No low-cost company could survive a crash. This is because media and most potential customers will react to such an event by thinking "Huh. They're low-cost, so they're unsafe, that's why they had this crash".
Despite being totally wrong, this would be the natural way of thinking of most people. Because of this, a low-cost airline can not "afford" an accident, and thus they invest a lot in flight safety.
No evolution
Some older airlines tried to go low-cost, or to have a low-cost subsidiary, but this is probably not possible. First the airline company will suffer from it, and customers would become unclear if the company is low-cost or not.
Secondly, such a mixed company would need the classical infrastructure, so no cost reduction can be expected here.
