The U.S. Department of Transportation released their airline report card on luggage handling for March 2019 and, based on reports per 1,000 passengers flown, the top ten list is as follows:
1) Allegiant (1.54 incidents per 1,000 passengers)
2) Frontier (3.62)
3) Spirit (4.00)
4) Hawaiian (4.22)
5) Southwest (4.23)
6) Delta (4.39)
7) Alaska (5.05)
8) Jet Blue (5.09)
9) United (5.57)
10) American (7.44!)
It would seem the low cost carriers owned the month of March, with 4 of the top 5 airlines with the best luggage handling. American Airlines though, with their continuing issues with the grounded MAX aircraft and their ongoing contract disputes with their mechanics, stumbled through the month.
Travelers remember: anytime your bag is delayed, it is vital to fill out a delayed luggage report with the arriving airline. Many lazy agents will try to avoid the hassle, by telling passengers their bag will arrive on the next plane - but sometimes that is not the case. In most instances, passengers are required to initiate their baggage claim within four hours of arrival in order to receive any compensation after a bag is declared "lost," which is normally after 30 days. Absent the report, the claim may be denied.
It is also an excellent idea to place a copy of the itinerary inside the bag (last thing, just as you close it), which would allow airline agents to see who the bag belongs to and where they are if all of the baggage and identification tags are torn off. No need in sending the bag home if you are on day 2 of a 14 day trip! (The itineraries are a big help to airline agents.)