The G650's passenger cabin is 14-in. wider, 3-in. higher and substantially longer than that of the G550. Finished dimensions are 8.2 ft. wide, 6.3 ft. tall and 42.9 ft. overall length from cockpit divider to the baggage compartment bulkhead. The floor is a full 15-in. wider than the G550's, making it the widest among purpose-built business aircraft. The aircraft's new four radii cross-section was inspired by the non-circular design of G150, one that maximizes head, shoulder and elbow room for the available cross-section. The G650 has 28% more total cabin volume and 30% more floor area, along with 3 in. more legroom in each seating area than the G550. Gulfstream's signature wide oval windows are 16% larger and 3.4-in. higher for better viewing. The 16 cabin windows are by far the largest of any business jet. Yet, the linear weight of the fuselage pressure vessel is essentially the same as that of the G550. That's impressive structural efficiency, considering the aircraft has the highest pressurization of any current production ultra-long-range aircraft.

The G650 has the first electrically controlled and latched door in an FAR Part 25 aircraft. It's 6.3 ft. high by 3.0 ft. wide with an air-stair design having illuminated treads, sturdy left and right hand rails and an offset hinge that increases headroom when entering the vestibule. There is no manual door handle, other than a maintenance door release buried behind the cover. Electric locking and unlocking, along with electric actuation, enables the flight attendant or the flight crew to open or shut the door from their crew stations.

The aircraft has 27.5-in.-long left and 33.5-in.-long right electrical equipment racks in the forward cabin. Gulfstream engineers elected to retain the above-floor equipment bays rather than move the equipment under the floorboards because they say the bays provide better equipment cooling and much easier maintenance access to components for technicians.

A dozen pre-set “Select” interior configurations are available for the G650. The aircraft we flew for this report had the Universal 13 layout, featuring forward crew area with crew rest compartment, galley and lavatory, three seating areas in the main cabin, an aft lavatory and an internally accessible baggage compartment beyond that. The fit and finish of Gulfstream's interior furnishings and completion work are superb.

On the right side of the crew area, there is a hanging storage closet for the crew and an 80.4-in.-long crew rest compartment with solid, sound attenuating pocket door, a cabin window and a berthable 24-in.-wide chair. Ahead of the chair, there is a 22-in.-long by 24-in.-wide foldout worktable that stores in the side panel and a 17-in. entertainment monitor on the forward bulkhead. A JetBed collapsible mattress is required equipment to configure the chair as a qualified crew berth in accordance with Part 135.

Aft of the entry door, there is another 11-in.-wide hanging closet and a 51-in.-long left-side crew lavatory with solid pocket door, window, mirror with indirect lighting, storage compartments and vacuum toilet. With the cushion cover folded down over the potty, the crew lav doubles as an additional seated rest area for a crewmember.

Next aft, there is a 52.5-in.-long galley that is split into left and right halves, each of which has a window. The left side has a wet sink with water sterilizer and counter space with pullout work surface, two beverage pots, microwave oven and convection oven in a stainless-steel faced stack, along with tableware storage, plus a dirty dish drawer and waste bin. The right side has an overhead stemware rack, 10-bottle wine rack, two ice drawers, a 4.5-cu.-ft. refrigerator/freezer and storage drawers. The forward end of the galley may be shut off from the lavatory and crew rest compartment with an accordion curtain. The aft side of the galley has an electrically operated pocket door to separate the compartment from the 26.7-ft.-long main seating area.

The main seating area is quite similar to that of the G550, but each of the three sections is appreciably longer, wider and taller. Each section has a pair of windows with electric shades, universal 115 VAC/60 Hz power outlets, headphone jacks and PDA charging docks. There also is a 115 VAC/60 Hz external power connection to provide ground power for a cabin vacuum cleaner and passenger systems.

On the right front bulkhead, there is a 26-in. LCD entertainment system monitor. The front section has a four-seat club section with the aft two seats being electrically powered with back and seat cushion heat, electric lumbar control and back cushion massage. The chairs are 28 in. wide overall with 21 in. net width between the armrests. Electrically actuated, left- and right-side, 28-in.-long by 29-in.-wide foldout worktables extend from and retract into side panels at the touch of a button. Pairs of facing chairs convert into sleeping berths. Electrically powered and heated chairs may be installed at other locations, but each adds about 30 lb. of weight to the aircraft. Also, 12.1-in. personal entertainment monitors are available as options.

The center section has a left-side, 45-in.-wide, four-seat conference grouping with power outlets, HDMI video port and RJ11 satcom phone jack. On the right side, there is a 7.1-ft.-long credenza that houses a 26-in., electrically actuated, pop-up LCD monitor, office equipment and chilled wine rack. Each 18-in.-wide chair can be tracked 9 in. fore and aft. The aisle side chairs track inboard 5 in. for additional elbowroom. A 32-in.-long by 45-in.-wide foldout conference table between the facing chairs extends and retracts on telescoping legs. The four-seat conference grouping converts into a double bed.

Also in the center section, there are twin, left- and right-side overwing emergency exits that are similar to those in early Gulfstream jets, but they're considerably larger. Rather than simply being removable windows, the four new emergency exits are 2.2-ft.-high by 2.7-ft.-wide doors in the fuselage walls with integral windows in their centers. The change more than doubles the size of the emergency exit openings compared to those on the G550.

The aft section of the cabin has an 80-in.-long three-place divan on the right side with a 3.95-cu.-ft. storage cabinet at the front and a first-aid cabinet at the rear. There are two facing chairs on the left side that convert into a single berth. So, the aircraft sleeps six passengers on overnight trips. The aft section may be enclosed with bulkheads, converting it into a private stateroom.

Aft of the main seating section, there is a 48-in.-long lavatory with vacuum toilet and 13-in.-wide closet on the left and wet sink plus vanity cabinet on the right. The lavatory has no windows.

The back side of the lavatory is a secondary pressure bulkhead with access door to the 195-cu.-ft., 2,500-lb. capacity aft baggage compartment. The compartment is 11% larger in volume than that of the G550. Inflight access is restricted to FL 400 and below, thus it's practically only accessible during climb-out and descent. The 3.6-ft.-wide by 2.6-ft.-high exterior door is 8% larger than on the G550 and the sill height is 4 in. lower for easier loading.