It's becoming a major headache. The FAA lists incidents every six months as a spreadsheet.[1] 474
incidents in the last reporting period. One midair collision with a drone, not serious.

There are many reports of UAVs interfering with forest fire fighting operations. This is probably the biggest single problem with real impact.

KELSO, WA/UAS INCIDENT/1507P/ZSE ARTCC REPORTED EUROCOPTER AS350 (US FOREST SERVICE) OBSERVED A 4 ROTOR UAS, 32 MILES NE SOUTHWEST WASHINGTON RGNL ARPT, BETWEEN 3,400 AND 5,000 FEET, IN CLOSE AND UNSAFE PROXIMITY TO THE HELO. WHEN THE FOREST SERVICE ATTEMPTED TO CONTACT THE INDIVIDUAL, HE LOADED THE UAS INTO HIS VEHICLE AND FLED THE SCENE. SKAMINIA COUNTY SHERIFF OFFICE NOTIFIED.

SANTA CLARITA, CA/UAS INCIDENT/1447P/ZLA ADVISED UAS OPERATIONS REPORTED IN THE VICINITY OF THE SAND FIRE, NEAR SANTA CLARITA. NO IMPACT TO FIRE FIGHTING ACTIVITIES OTHER THAN MOVING WHERE THE AIR ASSETS ARE ""DIPPING"" FOR WATER. FIRE AUTHORITIES ARE WORKING WITH LA CO SHERIFF AND ARE ACTIVELY SEARCHING FOR OPERATOR.

NATIONAL FOREST SERVICE OFFICE NOTIFIED SALT LAKE ARTCC OF AN UNAUTHORIZED WHITE PHANQUADCOPTER WITH A CAMERA OPERATING WITHIN THE CONFINES OF A FIRE-FIGHTING TFR BELOW 500 FEET, 15 NE SALMON, ID. AIRBORNE FIRE-FIGHTING OPERATIONS WERE HALTED UNTIL CONTACT WAS MADE WITH THE UAS OPERATORS AND UAS OPERATIONS CEASED. UAS OPERATORS DEPARTED AREA PRIOR TO LEO ARRIVING. VEHICLE LICENSE PLATE WAS OBTAINED.

IDAHO CITY, ID/UAS INCIDENT/2015P/UNITED STATES FORESTRY SERVICE ADVISED THEY HAD SUSPENDED THE AIR ATTACK MISSION IN TFR 4961 DUE TO A UNAUTHORIZED UAS FLYING IN THE TFR. THE TFR WAS REPORTED BY SOMEONE ON THE GROUND WHO STATED IT WAS OPERATING 4,000 FEET ABOVE THE TREES. UNITED STATES FORESTRY SERVICE REPRESENTATIVE STATED HE WAS GOING TO GATHER MORE INFORMATION ON THE INCIDENT AND CALL IT IN TO SALT LAKE CITY ARTCC.

CALL FROM THE CUT FIRE SAN BERNADINO NATIONAL FOREST TO REPORT A UAS INTERFERING IN FIRE FIGHTING EFFORTS IN THE CUT FIRE. SHE STATED THAT AIR SUPPORT WAS FOLLOWING THE UAS AND THAT LAW ENFORCEMNT WAS ON THE WAY. THE LOCATION WAS REPORTED TO BE 15 ON THE EAST SIDE OF THE 15 FREEWAY OVER THE CAJON PASS AT 040. IT WAS ALSO MAKING CIRCLES OVER THE SUMMIT TRAIL.

LAX and JFK have multiple incidents of UAVs in the traffic pattern.

LOS ANGELES, CA/UAS INCIDENT/1005P/LAX ATCT ADVISED COMPASS, E170, LAX - SFO, ON DEPARTURE CLIMB OUT FROM LAX REPORTED PASSING UNDER A HOVERING UAS AT APPROXIMATELY 130 FEET. THE UAS THEN PROCEEDED SOUTHWEST BOUND. NO EVASIVE ACTION REPORTED.

JFK/UAS INCIDENT/1945E/JFK ATCT REPORTED OBSERVED A RED AND ORANGE UAS AT 1,100 FEET 4 MILE FINAL RUNWAY 13. NYPD AVIATION UNIT NOTIFIED ON FREQUENCY.

Two UAVs at 2500 feet in the traffic pattern:

"PRELIM INFO FROM FAA OPS: PITTSBURGH, PA/UAS INCIDENTS/0013E/EC135, REPORTED TWO UAS ONE RED AND THE OTHER WHITE AT 2,500 FEET APPX. 5.5 MILES SE OF PITTSBURGH ARPT. AN IMMEDIATE CLIMB WAS REQUIRED TO AVOID THE UAS.

This was probably harmless, but dumb:

WASHINGTON, DC/UAS INCIDENT/1430E/US PARK POLICE REPORTED UAS AT 100 FEET NEAR THE WASHINGTON MONUMENT FILMING A FITNESS VIDEO. USPP SEIZED THE UAS AND CITED OWNER; UAS NOT REGISTERED.

Minor midair collision. Possibly a UAS. 6500' sounds high, but Provo UT is already at 4500',
so this is only 2000' AGL:

PROVO, UT/AIR CARRIER/01-1857M/BEECH BE99 AFTER LANDING SLC REPORTED MINOR DAMAGE TO VERTICAL STABILIZER. NTSB AND FSDO INVESTIGATING AS POSSIBLE MIDAIR WITH UAS AT 6,500 FEET 10 E PROVO. INCIDENT NOT REPORTED WHILE AIRBORNE.

Incidents where evasive action was required:

FLORENCE, SC/UAS INCIDENT/1524E/EXPERIMENTAL APF3, REPORTED SEEING A QUAD COPTER UAS AT SAME ALTITUDE OF 3,500 FEET. ACFT CLIMBED 400 FEET TO AVOID. UNKN IF LEO WAS NOTIFIED.

RED BLUFF, CA/UAS INCIDENT/1118P/OAKLAND ARTCC ADVISED PIPER P28A, AT 2,800 FEET, OBSERVED A RED AND WHITE 6-8 FOOT TALL UAS 300 FEET BELOW ACFT 8 NNW RED BLUFF. PIC STATED EVERYTIME HE MANEUVERED, UAS MANEUVERED TOWARD THE ACFT. TEHAMA COUNTY SHERIFF NOTIFIED.

HOUSTON, TX/UAS INCIDENT/2150C/HELO, EC45, INBOUND TO HOUSTON MEDICAL CENTER AT 800 FEET ENCOUNTERED A RED QUADCOPTER UAS WITH AMBER LIGHTS AT 600 FEET FLYING OVER THE BUILDINGS. HELO MADE EVASIVE MANEUVER TO AVOID UAS. UAS CAME WITH IN .1 MILE OF HELO.

CHESTER, MA/UAS INCIDENT/1857E/BRADLEY TRACON REPORTED CESSNA C172, WHILE SSE BOUND AT 5,500 FEET, ENCOUNTERED A BLACK UAS WITH 1 ROTOR, 200 -300 FEET ABOVE AND TO HIS LEFT 5 NW CHESTER. ACFT TURNED RIGHT TO AVOID UAS. MA STATE PD NOTIFIED.

VFR AIRCRAFT, AT LEVEL FLIGHT REPORTED HAVING TO TAKE EVASIVE ACTION TO AVOID A VERY SMALL UAS.CONTROLLER REPORTED THAT THERE WAS NO TRAFFIC OBSERVED IN THE AREA. AIRCRAFT DID NOT RECEIVE ANY DAMAGE, LANDED SAFELY AT BAF.

Doing the right thing:

FARGO, ND/UAS INCIDENT/1755C/FAR ATCT ADVISED OWNER OF UAS WAS OPERATING UAS IN CLASS D AIRSPACE 1.5 MILES S FAR WHEN BATTERY IN REMOTE CONTROLLER DIED. THE UAS IS PROGRAMMED TO CLIMB TO 1,500 FEET AND HOVER. FAR ATCT REPORTED 3 GA BUSINESS ACFT WERE HOLDING FOR DEP AND 1 AIR CARRIER WAS INBOUND. OWNER CALLED BACK AND REPORTED 22 MIN LATER THE UAS SAFELY ON GROUND. AN INDIVIDUAL CALLED FARGO TOWER NOTIFYING US THAT HE WAS FLYING AN UNAUTHORIZED DRONE IN THE CLASS DELTA AIRSPACE AND THE CONTROLLER FOR THE DRONE HAD DIED. WHEN THE CONTROLLER FOR THE DRONE DIES, THE UAS HOVERS AT 1500 FEET. THE INDIVIDUAL SAID IT WOULD TAKE 15 TO 20 MINUTES TO CHARGE THE CONTROLLER AND GET THE DRONE WORKING AGAIN. AT 2317Z THE INDIVIDUAL CALLED BACK AND SAID THE UAS IS ON THE GROUND. THE DRONE WAS OPERATED NEAR CENTENNIAL BLVD, APPROX 1.5MI SOUTH OF THE AIRPORT.

[1] https://www.faa.gov/uas/resources/uas_sightings_report/