Date: 201411
Local time of day: 1801-2400
Location: SNA.Airport, CA
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach; Landing
Airspace: Class C SNA
ATC / advisory: Ground SNA; Tower SNA
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: ATC Issue All Types; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Procedure
Primary problem: Procedure

Narrative: On final approach; at ~1500AFL; another aircraft was cleared to Line Up And Wait. This aircraft was closely following another prior departure; and was advised that we were on approximately 7 mile final (we were more like 6 miles out). After the prior aircraft was launched; this aircraft was asked to advise prior aircraft in sight. Once that was confirmed; his takeoff clearance was issued when we were on about 3 mile final; at about 1200AFL. Our landing clearance was issued at about 800AFL; while that departing aircraft was still on the runway. That aircraft was finally off the ground as we descended through about 250' AFL. According to our ND; there was maybe 1.6 miles separation minimum as they accelerated while we were on short final. We discussed this situation on short final; that we could expect some jet blast during the roundout and flare.  Sure enough; at about 30 feet over the runway; SIGNIFICANT disturbance of the airflow was experienced. A normal; safe; landing was barely accomplished; in the touchdown zone; and a normal rollout was accomplished.  When we contacted ground control for taxi clearance; I had my FO ask ground for the facility phone number. Response from ground was; 'Did we do something wrong again?'. We chuckled a bit; but this is really a serious event. For several reasons:1. This is the shortest runway we operate this aircraft on to in the domestic system. Any instability in the last few seconds of the landing sequence can invite unnecessary risk.2. In this case; we had two pilots experienced in operating into this airport; so we expected it; and were confident in our ability to handle it.This event was so bad that my flight attendants asked about 'What happened there; right before landing?'. I explained that I would be calling the ATC facility (which I did; some 20 minutes after landing); and writing up a report (this ASAP).  Maybe not so bad in this situation; given that both pilots in this case operate routinely into and out of this airport; but we have to consider the situation when an out-of-base crew is given the same handling. Many Go Arounds will surely or; at least; should; happen.  I have previously called the tower by phone to complain of this handling; and have been assured they would make adjustments. It's been over a year since the last instance; but perhaps a reminder is needed. I haven't written a report in the past; though perhaps I should have.  I have to consider what would happen if the departing aircraft had delayed for any reason? We would have had to go around; with extremely minimum spacing on the departure leg. Obviously; we would have sidestepped a bit; but separation would have been minimal at best.  I have in the past refused a takeoff clearance on this runway when I observe traffic on final below about 1500 feet above the runway. Having been on the receiving end of that traffic spacing; I don't want to put another pilot in the position of experiencing the thrust of my engines when they're trying to plant their aircraft on the runway in my wake. Our pilots need to be warned of the likelihood of this ATC tower attempting to clear aircraft to take off when aircraft on approach are too close. Establish a definite limit; maybe something like a minimum of 1200-1500 feet; maybe 4 miles; on final; below which a departing aircraft will not be cleared for takeoff.In future; when I'm on final; I will have to carefully consider whether I'll accept a landing clearance when there is another aircraft departing when I'm below 1500 feet on approach.




Synopsis: B737-800 Captain reported encountering jet blast and resulting turbulence from an aircraft taking off shortly before landing at SNA. Reporter stated this tight spacing is common practice in SNA and he is not comfortable with it.