What's the difference between being on Reserve vs. being a Line Holder? I was pretty confused about these two terms before I got hired at the airlines and I heard many pilots toss those terms around like they were common knowledge. I was too cool to ask (can't let the guys see me drop my ego... haha), so I just waited until I was at the airlines to learn it all. But, I don't want you to be in the same boat, so here's your answer.
Being on reserve means being 'on call.' If a pilot calls in sick, or can't get to work because of weather, or has a family emergency, or gets stuck in NYC because of a maintenance issue and the crew can't fly to SLC, etc, the company needs to have a pilot they can call to get the flight covered. There are a certain amount of pilots each month that are put on reserve to make sure each flight can still go out as planned even if the original plan does not work out.
When I got done with my initial training in May 2017, I was put on reserve. I bid for the days I wanted to be off, and for the most part, I got the days I wanted (though there's no guarantee I'd get the days I bid for, I always bid for exactly what I want). For the most part, I was on reserve on weekends (which is what I bid for as my husband and I wanted to minimize the time our son was with a sitter) and holidays because I was a bit junior.
The company I work for has a 12-hour callout, meaning if they call me, they have to give me a 12-hour notice before they expect me to report for work. As I live in Salt Lake and am based in SLC, a 12-hour notice is plenty of time to get my things together and get to work before my report time. However, I can get shortened down to only a 2-3 hour notice a few times a month (though I would still have to have a 12-hour notice to be shortened down to a 2-3 hour notice). When this happens, I make sure my bag is packed and ready to go, and I don't stray further than about 20 minutes from my house. These short call days are not my favorite, but I understand the company needs pilot they can call last minute sometimes.
Some pilots hate being on reserve, and I was that pilot when I worked at the regionals, but I LOVE it now. The company I work for is great about giving as much heads up as they can, and the trips that depart out of SLC are usually pretty enjoyable. I was called with only a 2-hour notice on Thanksgiving night a few years back, but it was a flight to Hawaii... it was a bummer to leave at 9:15pm, but being in Hawaii the next day was pretty awesome. The summer of 2017 (my first year at the company) I got used nearly every day I was on reserve, but 99% of the time I had at least a 30 hour notice, so I had plenty of time to wrap my mind around working instead of enjoying some R&R at home.
After about a year at the company, I could have been a line holder if I was willing to work 10-day trips out of SEA, but I didn't want to be gone from my family for that long, so I purposefully bid to be on reserve. In fact, I got paid for working the entire month of February in 2018 without having to step foot onto the airport property. I was on reserve for 17 days, 6 of those I got shortened to short call, but I never got called out for a trip. It was a nice unexpected month off. :)
Being a line holder has its perks too. A pilot can be a line holder if they are senior enough to be able to bid for and have a schedule each month- they know when and where they'll be flying; no last minute 12-hour notice surprises. Having a schedule (or a line) is nice if you like to be able to plan things- are you going to be home to go to your neighbor's BBQ or your kid's soccer game? If you hold a line you are able to drop trips, pick up trips, or exchange trips with other pilots. There's a lot more flexibility in the days you want to work vs days you want off. When I can hold 4-day trips or less, I will definitely be bidding for a line.
I hope this clears up some confusion about what being on reserve vs being a line holder is. But if you still have questions, feel free to email me at firstname.lastname@example.org.