It's not hard to model the costing of a very generic DB plan, but there are a bunch of variables to consider. In the current market, with relatively high interest rates (relative to recent history, that is), you can take a baseline of a 45 YO pilot lifetime payout at 65 of $12,000/mo ($144k/yr) w/survivorship benefits to spouse (about the same age) is about $850k, plus or minus.

If you want to pump it up to $15,000/mo ($180k/yr), you're looking at a current value of $1.1 million.

As the pilot gets older, the cost increases.
Increase the payout, the cost increases.
Lower the interest rates, and the cost increases...a lot (not linear).

If you are starting from scratch, you'd have a whole range of demographics to blend out the cost, but the number gets big in a hurry. IF you are going to replace the DB, ideally you want that money back on a rough equivalent of what the current dollar value of the plan would be. For a 30 YO, that'd be about $400k. For a 64 YO, that's $2.2 million.

There are a colossal number of variables to consider, but understand just dropping the DB would involve a ton of complicated costing, and if you want an equivalent benefit, some people are going to get giant checks, and others not so much, and sometimes that's tough to explain despite the math.